Re: Oracle 11.2 on AIX 7.1 JFS2 mount options

Stefan, sometimes you are frightening me. :) Thanks, will look that paper up.

Still open questions: Is this SAP Note's advice still valid for AIX 7.x ? My big question is if O_CIOR really does the same per file as O_CIO does for the file system. The SAP note seems to tell otherwise.

But if I am not allowed to set CIO any more, how can I get concurrent WRITE capability?

-- 
Martin Klier | Performing Databases GmbH 
Managing Partner | Senior DB Consultant 
Oracle ACE 

martin.klier_at_performing-db.com | http://www.performing-databases.com 



> Von: "Stefan Koehler" <contact_at_soocs.de>

> An: "ORACLE-L" <oracle-l_at_freelists.org>, "martin klier"

> <martin.klier_at_performing-db.com>

> Gesendet: Mittwoch, 21. Dezember 2016 21:17:08


> Betreff: Re: Oracle 11.2 on AIX 7.1 JFS2 mount options





> Hey Martin,

> short answer - SAPnote #948294 is correct. Long answer on page 59/60 here:


> http://tinyurl.com/o6uj6mf





> However please make sure that the JFS2 block size (for redo file systems) is


> aligned with the redo log block size in case of direct or concurrent I/O

> - otherwise you gonna run into demoted I/Os and Oracle needs two I/Os for one

> (first concurrent I/O fails silently and the next falls back to normal

> I/O). You can trace this with AIX kernel tracing events 59B,59C.




> Best Regards


> Stefan Koehler





> Freelance Oracle performance consultant and researcher


> Homepage: http://www.soocs.de

> Twitter: _at_OracleSK


>> Martin Klier - Performing Databases GmbH <martin.klier_at_performing-db.com> hat am


> > 21. Dezember 2016 um 20:46 geschrieben:





> > Hi listers,



>> I am calling out for Oracle-on-AIX knowledge/experience bearers, and have a


> > question whether setting the "cio" mount option for datafiles, redo


> > logs and control files for DB version 11.2.0.4 on AIX 7.1 with JFS2 or not.




> > We are using filesystemio_options=setall for this customer setup.






> > The documentation situation is a bit confusing:



>> + MOS Recommendations For Using CIO/DIO For Filesystems Containing Oracle Files


> > On AIX (Doc ID 960055.1) says:


>> "You need to set the CIO flag explicitly if you are not using


> > filesystemio_options=setall (or not using JFS2).


> > The CIO/DIO recommendations for filesystems containing Oracle Files are:

> > Data Base Files (DBF)

> > Use CIO or no mount options for extremely sequential I/O"


>> + SAP OSS Note 948294 - AIX JFS2: mount options to use with Oracle 10g / 11g


> > says:


> > "AIX 6.1 with Oracle >= 11.2.0.2:

>> AIX 6.1 introduced a new open flag O_CIOR which is same as O_CIO, but this


> > allows subsequent open calls without CIO. The advantage of this


>> enhancement is that other applications like cp, dd, cpio, dbv can access


> > database files in read only mode without having to open them with CIO.


> > Starting with Oracle 11.2.0.2 when AIX 6.1 is detected, Oracle will

> > use O_CIOR option to open a file on JFS2.

> > Therefore you should no longer mount the filesystems with mount option -o cio

>> Please remove the mount option "-o cio" if you are running Oracle 11.2.0.2 on


> > AIX 6.1 to avoid the following error messages:


> > cp: A system call received a parameter that is not valid.

> > 0653-902 Cannot open the specified file for reading.

> > DBV-00100: Specified FILE not accessible

> > errno(22) A system call received a parameter that is not valid."




> > + The Oracle "Database Administrator's Reference" says:


>> "Note: For Oracle Database 11g Release 2 (11.2.0.2) and later, on AIX 6.1


> > systems, Oracle recommends that you do not use the cio option on a JFS2


> > file system."




> > The IBM papers on that are REALLY GOOD but are all a bit outdated:


> > "AIX Performance: Configuration & Tuning for Oracle & Oracle RAC (Vijay Adik)"

>> "Oracle DB and AIX Best Pratices for Performance & tuning (Ronan Bourlier & Loïc


> > Fura)"







> > Simple question:


>> I have massively concurrent IO on datafiles (usual read/write activity) and redo


> > logs (streams capture) with many (so far unavoidable) "db file


> > sequential read" and "log file sync" waits.


>> Should I activate JFS2 mount option -cio for my data files and redo log file


> > systems?





>> Maybe that's more a starting point for a discussion rather than an end. I'd love


> > to understand better how the mechanics behind changed in 11.2.0.4


> > and AIX 7.x.




> > Thanks a lot in advance!





> > Martin Klier





> > --

> > Martin Klier | Performing Databases GmbH


> > Managing Partner | Senior DB Consultant

> > Oracle ACE




> > martin.klier_at_performing-db.com | http://www.performing-databases.com


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