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  • 1.  Max LUN size with Oracle

    Posted 17 hours ago

    Section 5.9.1 of Redbook "Oracle on IBM Power Systems" (sg248485) recommends to limit LUNs to 512 GB.  Is that recommendation still considered current?

    Trying to spec a new LPAR for oracle database server installation, and the database is currently 16TB in size.

    Keeping with the multiple of 8 for # of LUNS, start with 48 LUNS that are 400GB, and every few years ask SAN team to expand the LUNS by 50GB, to accommodate for growth?



    ------------------------------
    Gerald Stephens
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  • 2.  RE: Max LUN size with Oracle

    Posted 16 hours ago
    On Wed, Nov 05, 2025 at 06:00:48PM +0000, Gerald Stephens via IBM TechXchange Community wrote:
    > Section 5.9.1 of Redbook "Oracle on IBM Power Systems" (sg248485)
    > recommends to limit LUNs to 512 GB. Is that recommendation still
    > considered current?

    That does sound really small. I use 1T or 2T LUNs, because I want at
    least 4 LUNs in any VG for interdisk PP striping. If you have growth,
    always add another 4 LUNs minimum to avoid hot LUNs.

    Why not use 16 x 1T LUNs, and a scalable VG? You can add 4 x 1T for
    growth each year with reasonable balance and not have to do a reorgvg.

    I'd also suggest using multiple filesystems in the VG. Don't have a
    filesystem that would take longer to fsck than you can handle
    downtime. For instance, you might have your 16TB VG, but make each
    JFS2 filesystem 4TB (ie: /u01-/u04). If you have to fsck, you can run
    4 FS in parallel.

    Be sure to doublecheck your hdisk attributes to enable active/active
    pathing, which may need no_reserve set. Increase your queue depth as
    well.

    Good luck!

    ------------------------------------------------------------------
    Russell Adams Russell.Adams@AdamsSystems.nl
    Principal Consultant Adams Systems Consultancy
    https://adamssystems.nl/


    Original Message


  • 3.  RE: Max LUN size with Oracle

    Posted 5 hours ago

    Dear Gerald, 

    regarding the LUN limit , you have to consider a lot of limitation that control the LUN size, ex:

    if there is oracle data guard or if there is a storage replication as well as it depends on the storage brand and replication way. all of theses information need to know from each team before you take the LUN size decision.

    From my experience working in OS and storage department together to support and work with database teams, usually the LUN size is smaller or equal 2 TB. 



    ------------------------------
    Hashem Al-Qaisi
    Senior Systems Engineer
    Jordan Business Systems
    ------------------------------

    Original Message


  • 4.  RE: Max LUN size with Oracle

    Posted 2 hours ago

    Hi

    if you asking for LUN size on AIX it self ,the maximum LUN size on AIX is limited by the storage subsystem and the AIX version, with specific limits potentially , please check below IBM link for limitations for logical storage management 

    https://www.ibm.com/docs/en/aix/7.3.0?topic=concepts-limitations-logical-storage-management


    but for Oracle DB lun size i think better to check the recommendations from Oracle it self ,    Oracle databases on AIX you have to consider both performance and manageability and it's ASM ?

    so better the recommendation for Oracle LUN to provide from DBA

    Thanks



    ------------------------------
    Anas AlSaleh
    IBM Power Systems Software Specialist
    Saudi Business Machines ( SBM )
    Riyadh
    ------------------------------

    Original Message


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