[IQUG] IQUG Digest, Vol 67, Issue 8

Mumy, Mark mark.mumy at sap.com
Mon Aug 13 07:20:27 MST 2018


Periodically check my blogs, too.  Some of these ideas get posted up there.

My Blogs: https://blogs.sap.com/author/markmumy/

Mark

========================

Sent from my mobile device

On Aug 13, 2018, at 06:40, Steve Shen <sshen at sscinc.com<mailto:sshen at sscinc.com>> wrote:

Hi Mark

Good morning!

Thank you very much for the very detailed explanation and professional advices.

I really appreciated it.

Kind regards,

Steve Shen

-----Original Message-----
From: Mumy, Mark [mailto:mark.mumy at sap.com]
Sent: Friday, August 10, 2018 5:24 PM
To: Steve Shen; 'iqug at iqug.org<mailto:iqug at iqug.org>'; 'rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com>'; Baker, Chris
Subject: Re: IQUG Digest, Vol 67, Issue 8

It's not mandatory.  What is in the guides is the minimum to get you to IQ 16.   It's more a matter of wanting to take advantage of new features than stay with the legacy setup and structures.

Here's what doing the minimum leaves you with:
-- No n-bit indexes
-- Legacy 1/2/3 byte FP indexes and legacy query performance on them
-- All variable width data is still fixed width at the max length (varchar(100) is still 101 bytes in memory)
-- No query optimizations for char/varchar data
-- Larger database, no compression improvements (nbit and varchar/varbinary compress significantly over IQ 15)

So, if you want to just be current with IQ, then there is no need rebuild anything.  If you want to use any new features, optimizations, performance enhancements, bug fixes, etc then you want to rebuild all columns.  There were just to many changes when we went to IQ 16 that had to be done at such a low level; the likes of which we haven't seen before with IQ.  That low level work was required to prepare IQ for the future and give it the ability to scale into tens of PB of data.

I don't know of any IQ 15 customers that were even close to the PB range.  I don't know of but a few that were over 50TB or so.  The community where this would have had a huge impact and be time consuming only came into those sized because of what IQ 16 can handle.  Remember, too, that many customers chose to do a net-new IQ 16 deployment rather than an in-place upgrade simply to refresh hardware.

No, you don't have to do it, but the benefits really do outweigh the time to do it.  I always advise that you start with the heaviest used items first.  It doesn't have to be done before anyone can use it, but it makes sense to get the most frequently used stuff done first so that those users can benefit.  Then, as cycles permit, rebuild the less frequently used objects.

I'll leave you with this, too.  A move to IQ 16 shouldn't likely be done on the same hardware.  Quite a lot of the internals and memory sizing have changed.  So much that the memory sizing guidance has increased.  IQ 16 can also handle significantly more IO by running parallel, so an increase in storage throughput may be necessary as well.

And I always, always, always, advise turning OFF the IQ 15 compatibility stuff.  When you do an inplace upgrade, certain options are turned on (like the IQ 15 optimizer and such).  No sense moving to IQ 16 and leaving the old stuff in place.

And don't forget that ALL of the system options (DML_options, Core_Options, etc) need to be reset to default:
       set option public.DML_optionsXXX=;

The "=;" tells IQ to reset the value to default.  I had one customer that didn't do this.  They had an old option set from their IQ 15 days.  They never visited those options to see if they had the same behavior (they likely don't) or if they are still needed (they likely aren't).  Just 1 option caused a 30-40% slowdown in every single query!

Bigger picture, all options that you've set away from default should be reviewed when migrating to IQ 16.  I put this together, which I probably should blog, for a few customers:

SAP IQ Options
There are a core set of options that are used internally by engineering to set SAP IQ behavior.  When opening cases with SAP Support you may be asked to use some of these options as a workaround for an issue.  It is imperative that these options be reviewed with every version change to SAP IQ.  Changes to patch levels (4-8 times per year), service packs (1-2 times per year), and major versions (every 1-3 years) apply.  Because these options are controlled by engineering and are for internal use, they are not documented, and can have behavior changes with the next patch level, service pack, or major version updates.

Not checking these options can have a drastic effect on performance.  For instance, one query that was running in 1hr 15min, had four options set and not changed since IQ 15.4 was released.  These options changed behavior over the past few years and consequently, query performance was impacted.  When the options were set back to default, the query now ran over 35% faster, in just over 45 minutes.

The most critical options to watch are those that begin with these phrases:
•       ddl_options
•       mpx_options
•       dqp_options
•       core_options
•       dml_options

This does not mean that all options should not be reviewed, only that the above options can have a dramatic effect on performance.

Mark

Mark Mumy
Strategic Technology Incubation Group
SAP Global Center of Excellence |  SAP
M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com>
My Blogs: https://blogs.sap.com/author/markmumy/

https://sap.na.pgiconnect.com/I825063
Conference tel: 18663127353,,8035340905#

On 8/10/18, 1:38 PM, "Steve Shen" <sshen at sscinc.com<mailto:sshen at sscinc.com>> wrote:

   Today's Topic:
           Was it mandatory to rebuild all the default indexes/columns while migrating IQ instances from version 15.4 to 16.0?
           Was there a way to waive the efforts of rebuilding all default indexes/columns?

   One of my colleagues strongly questioned the needs to rebuild all the default indexes/columns while migrating IQ instances from version 15.4 to 16.0/ 16.1.

   He gave me his reasoning:  Who would spend so much time in rebuilding so many default indexes on so many columns for multiple PB or TB of IQ databases?  There must be a short-cut available for those companies using multiple PB or TB of IQ databases!

   While searching this subject, I felt very strange why to rebuild indexes, especially the default indexes/columns, was not documented in the following " SAP® Sybase® IQ 16 Best Practices Guide".  The only thing that is required is to issue ALTER DATABASE UPGRADE based on the doc.

   The following could be found on page 17 of the following document:
   https://www.sap.com/documents/2017/10/b6034a59-da7c-0010-82c7-eda71af511fa.html

   "
   Migrating From IQ 15 To IQ 16 (Alter Database Upgrade)
   • The changes in SA between IQ 15.x and IQ 16 do NOT require an unload/reload of the IQ Catalog.
   • Migrating from IQ 15.x to IQ 16 only requires running the ALTER DATABASE UPGRADE command.
   • Read the Migration  chapter in the SAP Sybase IQ 16 user documentation for detailed instructions.
   "

   Was there any short-cut that can waive us from rebuilding all those default indexes/columns?  Please advise.

   Thank you.

   Regards,

   Steve Shen

   -----Original Message-----
   From: Mumy, Mark [mailto:mark.mumy at sap.com]
   Sent: Friday, July 06, 2018 4:40 PM
   To: Steve Shen; 'iqug at iqug.org<mailto:iqug at iqug.org>'; 'rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com>'; Baker, Chris
   Subject: Re: IQUG Digest, Vol 67, Issue 8

   Don't forget that as part of the migration you will need to rebuild your indexes, especially the default indexes/columns.

   Mark

   Mark Mumy
   Strategic Technology Incubation Group
   SAP Global Center of Excellence |  SAP
   M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com>
   My Blogs: https://blogs.sap.com/author/markmumy/

   https://sap.na.pgiconnect.com/I825063
   Conference tel: 18663127353,,8035340905#

   On 7/6/18, 3:35 PM, "Mumy, Mark" <mark.mumy at sap.com<mailto:mark.mumy at sap.com>> wrote:

       That's a good process.  The backup/restore allows you to not have to install a version that may or may not work.

       Two ways to go here....  Since you are migrating and going to have to test, you could go with IQ 16.0 or IQ 16.1.  16.1 gives you a longer life as it is the most current release.  IQ 16 is end of life around Nov 2020, so some ways out, but worth keeping in mind.  Also, all new features are going into 16.1.  Something to consider at least.

       Mark

       Mark Mumy
       Strategic Technology Incubation Group
       SAP Global Center of Excellence |  SAP
       M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com>
       My Blogs: https://blogs.sap.com/author/markmumy/

       https://sap.na.pgiconnect.com/I825063
       Conference tel: 18663127353,,8035340905#

       On 7/6/18, 3:07 PM, "Steve Shen" <sshen at sscinc.com<mailto:sshen at sscinc.com>> wrote:

           Topics:
           1. Cross platform migrations from IQ version 15.4 at Solaris X64 to IQ version 16.0 at Linux (Red Hat version 7.4).
           2. On the most recommended SP at IQ version 16.0 at Linux and Solaris X64

           Hi Mark,

           My existing IQ instances are version 15.4 at Solaris X64. I got the client agreement today to migrate it to 16.0 in the following one or two months.

           The more traditional way for the cross platform migrations will be to migrate IQ version 15.4 to version 16.0 at Solaris X64, take the full backups from IQ version 16.0 at Solaris X64 and load the backups to IQ version 16.0 at Linux. This will eliminate potential version incompatibility issues.

           Please let me know whether the following short-cut will work or not:
           1. I will take the full backups from IQ version 15.4 at Solaris X64.
           2. I will load the full backups from the prior step and load it to version 16.0 at Linux (Red Hat version 7.4).
           3. After the database is loaded to IQ version 16.0 at Linux (Red Hat version 7.4), I will start the IQ version 16 Linux at read-only mode and then issue "alter database upgrade".
           Notes: I prefer to not install IQ version 15.4 to Linux (Red Hat version 7.4) because it may or may not work based on your feedback.

           BTW, which SP at IQ version 16 do you recommend for your clients?

           Your advise will save me time from trail-and-errors.

           Thank you very much for your reminder below.

           Best regards,

           Steve Shen

           -----Original Message-----
           From: Mumy, Mark [mailto:mark.mumy at sap.com]
           Sent: Friday, July 06, 2018 2:00 PM
           To: Steve Shen; 'iqug at iqug.org<mailto:iqug at iqug.org>'; 'rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com>'; Baker, Chris
           Subject: Re: IQUG Digest, Vol 67, Issue 8

           Just to reiterate...  IQ 15 doesn’t support RHEL 7 in any fashion.  It's never been tested, so it may work or it may not.  If it doesn't, well IQ 15 is out of support now, so you'd likely have to drop back to RHEL 6 until you get migrated to IQ 16 and the latest SP and patch.

           Mark

           Mark Mumy
           Strategic Technology Incubation Group
           SAP Global Center of Excellence |  SAP
           M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com>
           My Blogs: https://blogs.sap.com/author/markmumy/

           https://sap.na.pgiconnect.com/I825063
           Conference tel: 18663127353,,8035340905#

           On 7/6/18, 12:43 PM, "Steve Shen" <sshen at sscinc.com<mailto:sshen at sscinc.com>> wrote:

               Hi all,

               You can ignore the third question because UNIX SAs decided using Red Hat 7.4 with the default file systems "xfs" on SSDs.

               They were not keen in considering Red Hat version 6.x anymore.

               Thank you.

               Regards,

               Steve
               -----Original Message-----
               From: Steve Shen
               Sent: Friday, July 06, 2018 8:59 AM
               To: iqug at iqug.org<mailto:iqug at iqug.org>; 'mark.mumy at sap.com<mailto:mark.mumy at sap.com>'; 'rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com>'; 'c.baker at sap.com<mailto:c.baker at sap.com>'
               Subject: RE: IQUG Digest, Vol 67, Issue 8

               Today's Topics:

                  1. Re: IQUG Digest, Vol 67, Issue 5 (Mumy, Mark)
                  2. Re: IQUG Digest, Vol 67, Issue 5 (Steve Shen)
                  3. Re: ext3 or ext4 or xfs in Linux (Steve Shen)

               I am adding item #3 above for today's discussion.

               The default file systems at Red Hat version 6.8 and Red Hat version 7.4 were ext4 and xfs respectively in my company.

               Based on my understanding, ext4 is superior to ext3 and xfs is superior to ext4 in general.

               The file system  ext4 allows us to disable journaling to make the file systems perform better.  Is this a common practice to disable journaling in IQ? Will we lose recovery due to turning off journaling?

               Was there a consensus in this IQ community how to determine to use ext3 or ext4 or xfs for any of the following stores?
               1.  IQ Simplex catalog store;
               2. IQ Simpelx data store;
               3. IQ Simplex temp store;
               4. IQ backup file system;

               Notes: We are going to use SnapMirror from the primary IQ machine to the DR host.

               Please let me know if you have the answers.  Thank you.

               Regards,

               Steve Shen

               -----Original Message-----
               From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of iqug-request at iqug.org<mailto:iqug-request at iqug.org>
               Sent: Thursday, July 05, 2018 12:41 PM
               To: iqug at iqug.org<mailto:iqug at iqug.org>
               Subject: IQUG Digest, Vol 67, Issue 8

               Send IQUG mailing list submissions to
                       iqug at iqug.org<mailto:iqug at iqug.org>

               To subscribe or unsubscribe via the World Wide Web, visit
                       http://iqug.org/mailman/listinfo/iqug
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               When replying, please edit your Subject line so it is more specific than "Re: Contents of IQUG digest..."


               Today's Topics:

                  1. Re: IQUG Digest, Vol 67, Issue 5 (Mumy, Mark)
                  2. Re: IQUG Digest, Vol 67, Issue 5 (Steve Shen)


               ----------------------------------------------------------------------

               Message: 1
               Date: Thu, 5 Jul 2018 16:26:16 +0000
               From: "Mumy, Mark" <mark.mumy at sap.com<mailto:mark.mumy at sap.com>>
               To: Steve Shen <sshen at sscinc.com<mailto:sshen at sscinc.com>>, "iqug at iqug.org<mailto:iqug at iqug.org>" <iqug at iqug.org<mailto:iqug at iqug.org>>
               Subject: Re: [IQUG] IQUG Digest, Vol 67, Issue 5
               Message-ID: <51C29F4D-3DDD-4A37-B14B-CF9A82D3081B at sap.com<mailto:51C29F4D-3DDD-4A37-B14B-CF9A82D3081B at sap.com>>
               Content-Type: text/plain; charset="utf-8"

               Just saw your questions on RHEL versions.

               See my other email....  Using the manuals from Sybase.com<http://Sybase.com> isn't advised as they are not kept up.  For platform specific stuff and OS certifications, you can only get the currently supported platforms from sap.com<http://sap.com>, here.  What we list in the manuals was the initial versions supported.  We don't update the manuals when we test newer OS versions, we always update the SAP PAM (product availability matrix).
               https://apps.support.sap.com/sap(bD1lbiZjPTAwMQ==)/support/pam/pam.html?smpsrv=https%3a%2f%2fwebsmp106.sap-ag.de#ts=0

               See the IQ 16 manual you point to is grossly out of date and only shows RHEL 5 and 6 as supported when the products were first released.  Use the above link and you will see that other versions are included as well.  That link also includes other platform related details that are important for IQ deployment on various platforms.  Here's the link to all Linux versions supported for IQ 16.0:
               https://apps.support.sap.com/sap/support/pam?hash=s%3D%26filter%3Dfavorites%257CT%26o%3Dmost_viewed%257Cdesc%26st%3Dl%26rpp%3D20%26page%3D1%26pvnr%3D67838200100900005877%26pt%3Dt%257COS%26fclfilter%3DG1%257CLINUX%2520ON%2520X86_64%26ainstnr%3D67838200104900016656

               Our support for OS versions is a tad relaxed.  If it says RHEL 6.2, that doesn?t mean it?s the only version we support.  That's the minimum version we support for the main release of RHEL 6.  Our policy is to support any of the dot releases at that or a higher level.  So not RHEL 6.2, but really RHEL 6.2+ or RHEL 6.x with a minimum of 6.2.  However you want to read it.

               With IQ 15.4, you can use whatever OS you want without fear of violating support.  OK, it's not quite THAT easy.  IQ 15.4 is no longer supported.  So any OS that you want to support would be just fine.

               Do you have an SAP S-number?  The SAP sites contain quite a lot of details on IQ deployments in the PAM, roadmaps, SAP Notes, and manuals.

               Mark

               Mark Mumy
               Strategic Technology Incubation Group
               SAP Global Center of Excellence |  SAP
               M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com>
               My Blogs: https://blogs.sap.com/author/markmumy/

               https://sap.na.pgiconnect.com/I825063
               Conference tel: 18663127353,,8035340905#

               ?On 7/5/18, 11:03 AM, "iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> on behalf of Steve Shen" <iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> on behalf of sshen at sscinc.com<mailto:sshen at sscinc.com>> wrote:

                   Today's Topics:

                   1. Re: What is the IQ performance penalty from using file
                         systems in Linux kernel version 2.6 and above? (Steve Shen)

                   2. Re: RedHat Enterprise Linux versions for IQ versions 15.4 and 16.0 (Steve Shen)

                   The following are for IQ 15.4 and 16.0 at Linux from the document link http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc10083.1540/doc/pdf/iqicglin.pdf and http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc10083.1600/doc/pdf/iqicglin.pdf

                   "
                   Supported Server Platforms
                   Sybase IQ is compatible with these platforms and operating systems.
                   * Red Hat Enterprise Linux 6.2 (Linux on POWER; 64-bit)
                   * Red Hat Enterprise Linux 6.2 x86-64, Advanced Server and Workstation Editions
                   * Red Hat Enterprise Linux 6.0 (Linux onPOWER;64-bit) - minimum patch level Update-2
                   * Red Hat Enterprise Linux 6.0 x86-64, Advanced Server and Workstation Editions -
                   minimum patch level Update-2
                   * Red Hat Enterprise Linux 5.5 (Linux onPOWER;64-bit) - minimum patch level Update-2
                   * Red Hat Enterprise Linux 5.5 x86-64, Advanced Server and Workstation Editions -
                   minimum patch level Update-2
                   * SuSE Linux Enterprise Server (SLES) 11.0 x86-64 - minimum patch level SP1
                   * SuSE Linux Enterprise Server (SLES) 11.0 (Linux on POWER; 64-bit) - minimum patch
                   level SP1
                   Supported Client
                   "
                   Red Hat Enterprise Linux 5.5 x86-64 or 6.0 x86-64 or 6.2 x86-64 are very old.

                   Can I used Red Hat Enterprise Linux version 6.8 or 7.4?  Please advise.  Thank you.

                   Regards,

                   Steve

                   -----Original Message-----
                   From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of iqug-request at iqug.org<mailto:iqug-request at iqug.org>
                   Sent: Thursday, July 05, 2018 11:42 AM
                   To: iqug at iqug.org<mailto:iqug at iqug.org>
                   Subject: IQUG Digest, Vol 67, Issue 5

                   Send IQUG mailing list submissions to
                           iqug at iqug.org<mailto:iqug at iqug.org>

                   To subscribe or unsubscribe via the World Wide Web, visit
                           http://iqug.org/mailman/listinfo/iqug
                   or, via email, send a message with subject or body 'help' to
                           iqug-request at iqug.org<mailto:iqug-request at iqug.org>

                   You can reach the person managing the list at
                           iqug-owner at iqug.org<mailto:iqug-owner at iqug.org>

                   When replying, please edit your Subject line so it is more specific than "Re: Contents of IQUG digest..."


                   Today's Topics:

                      1. Re: What is the IQ performance penalty from using file
                         systems in Linux kernel version 2.6 and above? (Steve Shen)


                   ----------------------------------------------------------------------

                   Message: 1
                   Date: Thu, 5 Jul 2018 15:41:43 +0000
                   From: Steve Shen <sshen at sscinc.com<mailto:sshen at sscinc.com>>
                   To: "'Mumy, Mark'" <mark.mumy at sap.com<mailto:mark.mumy at sap.com>>, Ron Watkins
                           <rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com>>, "Baker, Chris" <c.baker at sap.com<mailto:c.baker at sap.com>>,
                           "iqug at iqug.org<mailto:iqug at iqug.org>" <iqug at iqug.org<mailto:iqug at iqug.org>>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file
                           systems in Linux kernel version 2.6 and above?
                   Message-ID:
                           <0C03FF7E7FA66E41A61525750FD653399DC52633 at ykt1emxprd6.globeop.com<mailto:0C03FF7E7FA66E41A61525750FD653399DC52633 at ykt1emxprd6.globeop.com>>
                   Content-Type: text/plain; charset="utf-8"

                   Hi Mark,

                   The senior management had chosen ?ease? over ?performance?.

                   Thank you very much for your feedback.

                   Regards,
                   Steve
                   From: Mumy, Mark [mailto:mark.mumy at sap.com]
                   Sent: Thursday, July 05, 2018 11:10 AM
                   To: Ron Watkins; Baker, Chris; Steve Shen; iqug at iqug.org<mailto:iqug at iqug.org>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   Here?s what it boils down to for me?.

                   When you use a filesystem how much control do you have over every aspect of the filesystem, block sizes, continuous or striping methods, SAN communication, SAN/NAS block and stripe sizes, etc???

                   The worst answer is, I have no control over any of it.  Best case, you can control some or most of it.

                   With raw devices, you have complete control.  Or rather, IQ has complete control over everything outside of how the SAN storage is carved up.

                   I had one customer that used filesystems for IQ.  Those nice, big fat IOs that IQ likes to do were cut down to 2k for everything.  Which was then sent back to a SAN that like to do nice big IOs, too.  Another customer had a filesystem that used IOs that were slightly larger than what IQ could use and larger than the SAN block size definition.  It caused 2 IOs for every IO that IQ did because the filesystem write was bigger than a single block on the storage, so it had to be broken into 2 physical IOs.

                   Lastly, IQ will now want to open all filesystem devices with O_DIRECT.  So you have to make sure you filesystem supports that as well.  If not, then you leave yourself exposed for a situation where IO could be buffered but not on disk yet.

                   There is some merit to using journaling as it can help protect your filesystem.  With IQ, though, it will slow it down.  So you have a choice of performance or filesystem protection.

                   In the end, it comes down to ease or performance.  Do you want to easily implement IQ or have complete control over how IQ is implemented so that you can control performance?  There is no right or wrong here.  SAP has chosen that IQ will be implemented on filesystems when it is deployed as part of HANA in dynamic tiering.  That was done because HANA is on filesystem and it is easier to continue that with IQ/DT, though it can be changed if you know enough about HANA and DT to do so.  We made the choice to give up some on performance, for now, so that we could have an easier system to deploy.

                   I will say, though, that you had become very good friends with the system and storage administrators.  Chances are something will have to be changed so better to be trusted by them up front so changing something is easier.

                   Side note??. I would recommend against using the old Sybase.com<http://Sybase.com> man pages.  I know they are much easier to traverse, but they are quite old and not maintained.  This section still holds true, but other items have changed in the newer manuals.

                   Mark

                   Mark Mumy
                   Strategic Technology Incubation Group
                   SAP Global Center of Excellence |  SAP
                   M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com><mailto:mark.mumy at sap.com>
                   My Blogs: https://blogs.sap.com/author/markmumy/

                   https://sap.na.pgiconnect.com/I825063
                   Conference tel: 18663127353,,8035340905#

                   From: "iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org>" <iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org>> on behalf of Ron Watkins <rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com><mailto:rwatkins at dssolutions.com>>
                   Date: Thursday, July 5, 2018 at 8:08 AM
                   To: Chris Baker <c.baker at sap.com<mailto:c.baker at sap.com><mailto:c.baker at sap.com>>, 'Steve Shen' <sshen at sscinc.com<mailto:sshen at sscinc.com><mailto:sshen at sscinc.com>>, "iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>" <iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   Journaling is optional and can  be disabled using the following option to mkfs:
                   -O ^has_journal
                   The other comments I agree with, and always prefer RAW to FS.
                   Ron

                   From: Baker, Chris [mailto:c.baker at sap.com]
                   Sent: Wednesday, July 04, 2018 1:36 PM
                   To: Ron Watkins; 'Steve Shen'; iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>
                   Subject: RE: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   To add to Ron?s comments ?

                   Direct I/O and write-cache bypassing are good starts, but the filesystem choice WILL affect you as well, even as far as IQ page sizes vs. filesystem page sizes (IQ I/O is broken into smaller pieces).  The Linux I/O elevator can play here as well (anticipatory vs. cfq vs. deadline vs. noop) when defining I/O strategies, even for filesystem.

                   How the block device (holding the filesystem) is defined can also affect I/O.  Some SANs allow the blocks to be laid out consecutively, so even if the filesystem pages are smaller that IQ pages, the SAN can ?hold? the write for > 1 page, allowing better performance on the read/write as there is a better chance that consecutive blocks will be part of the same logical page.

                   I won?t even mention mirroring and the overhead that may cause.

                   Of course it goes without saying that you should not share the IQ filesystem for other purposes, in any case.

                   EXT4 is also a journaling filesystem.  It will log every,    single,    access ? and can slow down IO drastically.  You can turn off the EXT4 journaling aspects with various mount options and settings, effectively turning it into EXT3, and this can help performance.

                   In the end, you probably want to test RAW vs. Filesystem performance yourself to ensure it is within your own SLAs, performance criteria and I.T. specs.  Don?t overlook what I.T. ?thinks? you need or is only willing to provide, with what you MUST provide for your own SLAs to your end users/customers.

                   Chris

                   Chris Baker | Database Engineering Evangelist | CERT | PI HANA Platform Data Management | SAP T +1 416-226-7033<tel:+1%20416-226-7033> | M +1 647-224-2033<tel:+1%20647-224-2033> | TF +1 866-716-8860<tel:+1%20866-716-8860>
                   SAP Canada Inc. 445 Wes Graham Way, Waterloo, N2L 6R2<x-apple-data-detectors://17/1>
                   c.baker at sap.com<mailto:c.baker at sap.com><mailto:c.baker at sap.com> | www.sap.com<http://www.sap.com><http://www.sap.com/>

                   https://sap.na.pgiconnect.com/I826572
                   Conference tel: 1-866-312-7353,,9648565377#<tel:1-866-312-7353,,9648565377%23>

                   From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of Ron Watkins
                   Sent: Wednesday, July 4, 2018 4:02 PM
                   To: 'Steve Shen' <sshen at sscinc.com<mailto:sshen at sscinc.com><mailto:sshen at sscinc.com>>; iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   You can continue to use RAW devices under RHEL, and RHEL 7.4 still supports ext4 filesystems also.
                   Performance is generally dictated by the storage itself, and is less dependent on the ?format? of the storage.
                   Thus, if you have multiple disks providing multiple paths to storage you will see a greater improvement over a single disk.
                   RAW devices do perform better than filesystem, however, it?s not possible to put an exact value on how much better as they are both strongly dependent on the underlying storage.
                   Ron

                   From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of Steve Shen
                   Sent: Wednesday, July 04, 2018 12:15 PM
                   To: iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>
                   Subject: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   Today?s Topic:

                   (1). What is the IQ performance penalty from using file systems relative to using true raw partitions for main store and temporary store in Linux kernel version 2.6 and above?

                   We are considering to migrate our IQ Simplex from Solaris X64 to RedHat version 6.8 or 7.4. They are Linux kernel version 2.6 and above.

                   RedHat version 6.8 uses ?ext4? file system.  RedHat version 7.4 used ?xfs? file system.

                   This discussion is for IQ Simplex only.  I am very aware that using file systems will prevent me from converting the Simplex to Multiplex later.

                   Based on the documentation below, it seemed okay in using file systems at Linux kernel version 2.6 and above:

                   http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc00169.1600/doc/pdf/iqperf.pdf
                   ?
                   Controlling File System Buffering
                   On some file systems, you can turn file system buffering on or off. Turning file system buffering off usually reduces paging and improves performance.
                   To disable file system buffering for IQ Main dbspaces of existing databases, issue the following statement:
                   SET OPTION "PUBLIC".OS_FILE_CACHE_BUFFERING = OFF To disable file system buffering for IQ Temporary dbspaces of existing databases, issue the following statement:
                   SET OPTION "PUBLIC".OS_FILE_CACHE_BUFFERING_TEMPDB = OFF You can only set this option for the PUBLIC role. Shut down the database and restart it for the change to take effect.
                   This direct I/O performance option is available on Solaris UFS, Linux, Linux IBM, AIX, and Windows file systems only. This option has no effect on HP-UX and HP-UXi and does not affect databases on raw disk. In Linux, direct I/O is supported in kernel versions 2.6.x To enable direct I/O on Linux kernel version 2.6 and AIX, also set the environment variable IQ_USE_DIRECTIO to 1. Direct I/O is disabled by default in Linux kernel version 2.6 and AIX. IQ_USE_DIRECTIO has no effect on Solaris and Windows.
                   ?

                   It?s also documented by Mark that using file systems is normally slower than true raw partitions in Linux:

                   https://archive.sap.com/discussions/thread/3518966

                   Did any of us ever do apple-to-apple comparisons and measure the performance penalty relative to using true raw partitions?

                   Was it 5%, 10%, 15% or 20% performance penalty or more from using file systems instead of true raw partitions at Linux?

                   Thank you.

                   Happy Independency Day!
                   Steve Shen
                   SS&C Technologies

                   This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.
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               ------------------------------

               Message: 2
               Date: Thu, 5 Jul 2018 16:40:27 +0000
               From: Steve Shen <sshen at sscinc.com<mailto:sshen at sscinc.com>>
               To: "'Mumy, Mark'" <mark.mumy at sap.com<mailto:mark.mumy at sap.com>>, "iqug at iqug.org<mailto:iqug at iqug.org>"
                       <iqug at iqug.org<mailto:iqug at iqug.org>>
               Subject: Re: [IQUG] IQUG Digest, Vol 67, Issue 5
               Message-ID:
                       <0C03FF7E7FA66E41A61525750FD653399DC5397C at ykt1emxprd6.globeop.com<mailto:0C03FF7E7FA66E41A61525750FD653399DC5397C at ykt1emxprd6.globeop.com>>
               Content-Type: text/plain; charset="utf-8"

               Hi Mark,

               I should not go back to Sybase web-sites anymore.  I will go to SAP web-site from now on.

               Thank you for your reminder.

               Regards,

               Steve

               -----Original Message-----
               From: Mumy, Mark [mailto:mark.mumy at sap.com]
               Sent: Thursday, July 05, 2018 12:26 PM
               To: Steve Shen; iqug at iqug.org<mailto:iqug at iqug.org>
               Subject: Re: [IQUG] IQUG Digest, Vol 67, Issue 5

               Just saw your questions on RHEL versions.

               See my other email....  Using the manuals from Sybase.com<http://Sybase.com> isn't advised as they are not kept up.  For platform specific stuff and OS certifications, you can only get the currently supported platforms from sap.com<http://sap.com>, here.  What we list in the manuals was the initial versions supported.  We don't update the manuals when we test newer OS versions, we always update the SAP PAM (product availability matrix).
               https://apps.support.sap.com/sap(bD1lbiZjPTAwMQ==)/support/pam/pam.html?smpsrv=https%3a%2f%2fwebsmp106.sap-ag.de#ts=0

               See the IQ 16 manual you point to is grossly out of date and only shows RHEL 5 and 6 as supported when the products were first released.  Use the above link and you will see that other versions are included as well.  That link also includes other platform related details that are important for IQ deployment on various platforms.  Here's the link to all Linux versions supported for IQ 16.0:
               https://apps.support.sap.com/sap/support/pam?hash=s%3D%26filter%3Dfavorites%257CT%26o%3Dmost_viewed%257Cdesc%26st%3Dl%26rpp%3D20%26page%3D1%26pvnr%3D67838200100900005877%26pt%3Dt%257COS%26fclfilter%3DG1%257CLINUX%2520ON%2520X86_64%26ainstnr%3D67838200104900016656

               Our support for OS versions is a tad relaxed.  If it says RHEL 6.2, that doesn?t mean it?s the only version we support.  That's the minimum version we support for the main release of RHEL 6.  Our policy is to support any of the dot releases at that or a higher level.  So not RHEL 6.2, but really RHEL 6.2+ or RHEL 6.x with a minimum of 6.2.  However you want to read it.

               With IQ 15.4, you can use whatever OS you want without fear of violating support.  OK, it's not quite THAT easy.  IQ 15.4 is no longer supported.  So any OS that you want to support would be just fine.

               Do you have an SAP S-number?  The SAP sites contain quite a lot of details on IQ deployments in the PAM, roadmaps, SAP Notes, and manuals.

               Mark

               Mark Mumy
               Strategic Technology Incubation Group
               SAP Global Center of Excellence |  SAP
               M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com>
               My Blogs: https://blogs.sap.com/author/markmumy/

               https://sap.na.pgiconnect.com/I825063
               Conference tel: 18663127353,,8035340905#

               ?On 7/5/18, 11:03 AM, "iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> on behalf of Steve Shen" <iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> on behalf of sshen at sscinc.com<mailto:sshen at sscinc.com>> wrote:

                   Today's Topics:

                   1. Re: What is the IQ performance penalty from using file
                         systems in Linux kernel version 2.6 and above? (Steve Shen)

                   2. Re: RedHat Enterprise Linux versions for IQ versions 15.4 and 16.0 (Steve Shen)

                   The following are for IQ 15.4 and 16.0 at Linux from the document link http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc10083.1540/doc/pdf/iqicglin.pdf and http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc10083.1600/doc/pdf/iqicglin.pdf

                   "
                   Supported Server Platforms
                   Sybase IQ is compatible with these platforms and operating systems.
                   * Red Hat Enterprise Linux 6.2 (Linux on POWER; 64-bit)
                   * Red Hat Enterprise Linux 6.2 x86-64, Advanced Server and Workstation Editions
                   * Red Hat Enterprise Linux 6.0 (Linux onPOWER;64-bit) - minimum patch level Update-2
                   * Red Hat Enterprise Linux 6.0 x86-64, Advanced Server and Workstation Editions -
                   minimum patch level Update-2
                   * Red Hat Enterprise Linux 5.5 (Linux onPOWER;64-bit) - minimum patch level Update-2
                   * Red Hat Enterprise Linux 5.5 x86-64, Advanced Server and Workstation Editions -
                   minimum patch level Update-2
                   * SuSE Linux Enterprise Server (SLES) 11.0 x86-64 - minimum patch level SP1
                   * SuSE Linux Enterprise Server (SLES) 11.0 (Linux on POWER; 64-bit) - minimum patch
                   level SP1
                   Supported Client
                   "
                   Red Hat Enterprise Linux 5.5 x86-64 or 6.0 x86-64 or 6.2 x86-64 are very old.

                   Can I used Red Hat Enterprise Linux version 6.8 or 7.4?  Please advise.  Thank you.

                   Regards,

                   Steve

                   -----Original Message-----
                   From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of iqug-request at iqug.org<mailto:iqug-request at iqug.org>
                   Sent: Thursday, July 05, 2018 11:42 AM
                   To: iqug at iqug.org<mailto:iqug at iqug.org>
                   Subject: IQUG Digest, Vol 67, Issue 5

                   Send IQUG mailing list submissions to
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                   Today's Topics:

                      1. Re: What is the IQ performance penalty from using file
                         systems in Linux kernel version 2.6 and above? (Steve Shen)


                   ----------------------------------------------------------------------

                   Message: 1
                   Date: Thu, 5 Jul 2018 15:41:43 +0000
                   From: Steve Shen <sshen at sscinc.com<mailto:sshen at sscinc.com>>
                   To: "'Mumy, Mark'" <mark.mumy at sap.com<mailto:mark.mumy at sap.com>>, Ron Watkins
                           <rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com>>, "Baker, Chris" <c.baker at sap.com<mailto:c.baker at sap.com>>,
                           "iqug at iqug.org<mailto:iqug at iqug.org>" <iqug at iqug.org<mailto:iqug at iqug.org>>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file
                           systems in Linux kernel version 2.6 and above?
                   Message-ID:
                           <0C03FF7E7FA66E41A61525750FD653399DC52633 at ykt1emxprd6.globeop.com<mailto:0C03FF7E7FA66E41A61525750FD653399DC52633 at ykt1emxprd6.globeop.com>>
                   Content-Type: text/plain; charset="utf-8"

                   Hi Mark,

                   The senior management had chosen ?ease? over ?performance?.

                   Thank you very much for your feedback.

                   Regards,
                   Steve
                   From: Mumy, Mark [mailto:mark.mumy at sap.com]
                   Sent: Thursday, July 05, 2018 11:10 AM
                   To: Ron Watkins; Baker, Chris; Steve Shen; iqug at iqug.org<mailto:iqug at iqug.org>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   Here?s what it boils down to for me?.

                   When you use a filesystem how much control do you have over every aspect of the filesystem, block sizes, continuous or striping methods, SAN communication, SAN/NAS block and stripe sizes, etc???

                   The worst answer is, I have no control over any of it.  Best case, you can control some or most of it.

                   With raw devices, you have complete control.  Or rather, IQ has complete control over everything outside of how the SAN storage is carved up.

                   I had one customer that used filesystems for IQ.  Those nice, big fat IOs that IQ likes to do were cut down to 2k for everything.  Which was then sent back to a SAN that like to do nice big IOs, too.  Another customer had a filesystem that used IOs that were slightly larger than what IQ could use and larger than the SAN block size definition.  It caused 2 IOs for every IO that IQ did because the filesystem write was bigger than a single block on the storage, so it had to be broken into 2 physical IOs.

                   Lastly, IQ will now want to open all filesystem devices with O_DIRECT.  So you have to make sure you filesystem supports that as well.  If not, then you leave yourself exposed for a situation where IO could be buffered but not on disk yet.

                   There is some merit to using journaling as it can help protect your filesystem.  With IQ, though, it will slow it down.  So you have a choice of performance or filesystem protection.

                   In the end, it comes down to ease or performance.  Do you want to easily implement IQ or have complete control over how IQ is implemented so that you can control performance?  There is no right or wrong here.  SAP has chosen that IQ will be implemented on filesystems when it is deployed as part of HANA in dynamic tiering.  That was done because HANA is on filesystem and it is easier to continue that with IQ/DT, though it can be changed if you know enough about HANA and DT to do so.  We made the choice to give up some on performance, for now, so that we could have an easier system to deploy.

                   I will say, though, that you had become very good friends with the system and storage administrators.  Chances are something will have to be changed so better to be trusted by them up front so changing something is easier.

                   Side note??. I would recommend against using the old Sybase.com<http://Sybase.com> man pages.  I know they are much easier to traverse, but they are quite old and not maintained.  This section still holds true, but other items have changed in the newer manuals.

                   Mark

                   Mark Mumy
                   Strategic Technology Incubation Group
                   SAP Global Center of Excellence |  SAP
                   M +1 347-820-2136 | E mark.mumy at sap.com<mailto:mark.mumy at sap.com><mailto:mark.mumy at sap.com>
                   My Blogs: https://blogs.sap.com/author/markmumy/

                   https://sap.na.pgiconnect.com/I825063
                   Conference tel: 18663127353,,8035340905#

                   From: "iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org>" <iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org>> on behalf of Ron Watkins <rwatkins at dssolutions.com<mailto:rwatkins at dssolutions.com><mailto:rwatkins at dssolutions.com>>
                   Date: Thursday, July 5, 2018 at 8:08 AM
                   To: Chris Baker <c.baker at sap.com<mailto:c.baker at sap.com><mailto:c.baker at sap.com>>, 'Steve Shen' <sshen at sscinc.com<mailto:sshen at sscinc.com><mailto:sshen at sscinc.com>>, "iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>" <iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   Journaling is optional and can  be disabled using the following option to mkfs:
                   -O ^has_journal
                   The other comments I agree with, and always prefer RAW to FS.
                   Ron

                   From: Baker, Chris [mailto:c.baker at sap.com]
                   Sent: Wednesday, July 04, 2018 1:36 PM
                   To: Ron Watkins; 'Steve Shen'; iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>
                   Subject: RE: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   To add to Ron?s comments ?

                   Direct I/O and write-cache bypassing are good starts, but the filesystem choice WILL affect you as well, even as far as IQ page sizes vs. filesystem page sizes (IQ I/O is broken into smaller pieces).  The Linux I/O elevator can play here as well (anticipatory vs. cfq vs. deadline vs. noop) when defining I/O strategies, even for filesystem.

                   How the block device (holding the filesystem) is defined can also affect I/O.  Some SANs allow the blocks to be laid out consecutively, so even if the filesystem pages are smaller that IQ pages, the SAN can ?hold? the write for > 1 page, allowing better performance on the read/write as there is a better chance that consecutive blocks will be part of the same logical page.

                   I won?t even mention mirroring and the overhead that may cause.

                   Of course it goes without saying that you should not share the IQ filesystem for other purposes, in any case.

                   EXT4 is also a journaling filesystem.  It will log every,    single,    access ? and can slow down IO drastically.  You can turn off the EXT4 journaling aspects with various mount options and settings, effectively turning it into EXT3, and this can help performance.

                   In the end, you probably want to test RAW vs. Filesystem performance yourself to ensure it is within your own SLAs, performance criteria and I.T. specs.  Don?t overlook what I.T. ?thinks? you need or is only willing to provide, with what you MUST provide for your own SLAs to your end users/customers.

                   Chris

                   Chris Baker | Database Engineering Evangelist | CERT | PI HANA Platform Data Management | SAP T +1 416-226-7033<tel:+1%20416-226-7033> | M +1 647-224-2033<tel:+1%20647-224-2033> | TF +1 866-716-8860<tel:+1%20866-716-8860>
                   SAP Canada Inc. 445 Wes Graham Way, Waterloo, N2L 6R2<x-apple-data-detectors://17/1>
                   c.baker at sap.com<mailto:c.baker at sap.com><mailto:c.baker at sap.com> | www.sap.com<http://www.sap.com><http://www.sap.com/>

                   https://sap.na.pgiconnect.com/I826572
                   Conference tel: 1-866-312-7353,,9648565377#<tel:1-866-312-7353,,9648565377%23>

                   From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of Ron Watkins
                   Sent: Wednesday, July 4, 2018 4:02 PM
                   To: 'Steve Shen' <sshen at sscinc.com<mailto:sshen at sscinc.com><mailto:sshen at sscinc.com>>; iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>
                   Subject: Re: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   You can continue to use RAW devices under RHEL, and RHEL 7.4 still supports ext4 filesystems also.
                   Performance is generally dictated by the storage itself, and is less dependent on the ?format? of the storage.
                   Thus, if you have multiple disks providing multiple paths to storage you will see a greater improvement over a single disk.
                   RAW devices do perform better than filesystem, however, it?s not possible to put an exact value on how much better as they are both strongly dependent on the underlying storage.
                   Ron

                   From: iqug-bounces at iqug.org<mailto:iqug-bounces at iqug.org><mailto:iqug-bounces at iqug.org> [mailto:iqug-bounces at iqug.org] On Behalf Of Steve Shen
                   Sent: Wednesday, July 04, 2018 12:15 PM
                   To: iqug at iqug.org<mailto:iqug at iqug.org><mailto:iqug at iqug.org>
                   Subject: [IQUG] What is the IQ performance penalty from using file systems in Linux kernel version 2.6 and above?

                   Today?s Topic:

                   (1). What is the IQ performance penalty from using file systems relative to using true raw partitions for main store and temporary store in Linux kernel version 2.6 and above?

                   We are considering to migrate our IQ Simplex from Solaris X64 to RedHat version 6.8 or 7.4. They are Linux kernel version 2.6 and above.

                   RedHat version 6.8 uses ?ext4? file system.  RedHat version 7.4 used ?xfs? file system.

                   This discussion is for IQ Simplex only.  I am very aware that using file systems will prevent me from converting the Simplex to Multiplex later.

                   Based on the documentation below, it seemed okay in using file systems at Linux kernel version 2.6 and above:

                   http://infocenter.sybase.com/help/topic/com.sybase.infocenter.dc00169.1600/doc/pdf/iqperf.pdf
                   ?
                   Controlling File System Buffering
                   On some file systems, you can turn file system buffering on or off. Turning file system buffering off usually reduces paging and improves performance.
                   To disable file system buffering for IQ Main dbspaces of existing databases, issue the following statement:
                   SET OPTION "PUBLIC".OS_FILE_CACHE_BUFFERING = OFF To disable file system buffering for IQ Temporary dbspaces of existing databases, issue the following statement:
                   SET OPTION "PUBLIC".OS_FILE_CACHE_BUFFERING_TEMPDB = OFF You can only set this option for the PUBLIC role. Shut down the database and restart it for the change to take effect.
                   This direct I/O performance option is available on Solaris UFS, Linux, Linux IBM, AIX, and Windows file systems only. This option has no effect on HP-UX and HP-UXi and does not affect databases on raw disk. In Linux, direct I/O is supported in kernel versions 2.6.x To enable direct I/O on Linux kernel version 2.6 and AIX, also set the environment variable IQ_USE_DIRECTIO to 1. Direct I/O is disabled by default in Linux kernel version 2.6 and AIX. IQ_USE_DIRECTIO has no effect on Solaris and Windows.
                   ?

                   It?s also documented by Mark that using file systems is normally slower than true raw partitions in Linux:

                   https://archive.sap.com/discussions/thread/3518966

                   Did any of us ever do apple-to-apple comparisons and measure the performance penalty relative to using true raw partitions?

                   Was it 5%, 10%, 15% or 20% performance penalty or more from using file systems instead of true raw partitions at Linux?

                   Thank you.

                   Happy Independency Day!
                   Steve Shen
                   SS&C Technologies

                   This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.
                   This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.
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               End of IQUG Digest, Vol 67, Issue 8
               ***********************************
               This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.


           This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.




   This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.


This email with all information contained herein or attached hereto may contain confidential and/or privileged information intended for the addressee(s) only. If you have received this email in error, please contact the sender and immediately delete this email in its entirety and any attachments thereto.
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