AIX

AIX

Connect with fellow AIX users and experts to gain knowledge, share insights, and solve problems.

 View Only
Back to discussions
Expand all | Collapse all

New SSD Drive shown as pdisk

  • 1.  New SSD Drive shown as pdisk

    Posted Tue June 06, 2023 05:33 PM

    Greetings. 

    I wanted to use a pair of SSD drives, 400GB IBM FRU 00YY002 ST400FM243, for merrowed rootvg, OS AIX 7.2, Hardware Power 8231-E2C.

    The SSDs are recognized as  pdisks, not the usual hdisk after 'cfgmgr'.

    pdisk0 in location U78AB.001.WZSHVKK-P3-D4

    sissas0   FFFFFFFF  Available   PCIe x4 Planar 3Gb SAS Adapter

    pdisk0    00030000  Active      SSD Array Candidate    387.9GB 

    I cannot convert it to hdisk because  0940-120 JBOD format is not supported on SSD drives.

    Any other way I can set/convert it to hdisk?

    Thanks!

    --Kang



    ------------------------------
    Kang Sun
    ------------------------------


  • 2.  RE: New SSD Drive shown as pdisk

    Posted Tue June 06, 2023 06:05 PM
    Hi Kang

    Just a question: you already have two candidates (pdis0 and pdisk1 ??) for RAID HW based so why dont create a RAID10 using the adapter SSD?



    Original Message


  • 3.  RE: New SSD Drive shown as pdisk

    Posted Wed June 07, 2023 09:59 AM

    Thanks for replying.

    My situation is I made altinst boovg on a single SSD 400GB drive 

    # lspv
    hdisk0          00f832dff6ad79d4                    rootvg          active            
    hdisk4          00f832df91c2ef69                    altinst_rootvg  active      

    From sissas0 controller, it is shown as

    hdisk4    00000000  Available   SAS 4K Solid State Dr  400.0GB

    This one shown as hdisk so I can use it in a VG without using RAID0 
    Now I bought two refurnished SSD 400GB drives and I hope I can use one mirror rootvg in the future, but they are shown up as pdisk.

    I attempted to convert them to hdisk but get the error message that 0940-120 JBOD format is not supported on SSD drives.

    smit to "Delete an Array Candidate pdisk and Format to JBOD block size"

    I guess as you suggested I can build a RAID10 out of these two pdisks and buid rootvg on it.

    My question is this bootable? What about overhead?

    Thanks!

    --Kang



    ------------------------------
    Kang Sun
    ------------------------------

    Original Message


  • 4.  RE: New SSD Drive shown as pdisk

    Posted Wed June 07, 2023 02:57 AM

    You mean when you run "sissasraidmgr -U -z pdisk0" you get the error you quoted?



    ------------------------------
    Lech Szychowski
    ------------------------------

    Original Message


  • 5.  RE: New SSD Drive shown as pdisk

    Posted Wed June 07, 2023 04:59 AM

    https://www.ibm.com/docs/en/power8?topic=drives-solid-state-drive-configuration-rules

    Create a RAID-10 on top of the two pdisks, or a RAID-0 on each pdisk.



    ------------------------------
    José Pina Coelho
    IT Specialist at Kyndryl
    ------------------------------

    Original Message


  • 6.  RE: New SSD Drive shown as pdisk

    Posted Wed June 07, 2023 08:41 AM

    This is what we do with SAS disk before we install VIO on them so we have a pair of disk to mirror rootvg. Raid 0 sucks for rootvg especially for VIO

    This works with P8 and P9 SAS disk so your millage may varry

    Turn the pdisk back into an hdisk.

    1.      Run smit devices,  Disk Array, IBM SAS Disk Array, IBM SAS Disk Array Manager

    2.      Change/Show SAS pdisk Status

    3.      Delete an Array Candidate pdisk and Format to JBOD block size

    4.      Choose the right controller, and the right disk. And start the Format to a JBOD.

    5.      At the end it will automatically become an hdisk and you can exit.



    ------------------------------
    Douglas Probst
    ------------------------------

    Original Message


  • 7.  RE: New SSD Drive shown as pdisk

    Posted Wed June 07, 2023 10:57 AM

    >   Delete an Array Candidate pdisk and Format to JBOD block size

    This is exactly where I received the message:

    0940-120 JBOD format is not supported on SSD drives.



    ------------------------------
    Kang Sun
    ------------------------------

    Original Message


  • 8.  RE: New SSD Drive shown as pdisk

    Posted Mon June 12, 2023 04:13 PM

    I created a hdisk out of one pdisk as RAID0, and then converted RAID10 by adding the 2nd pdisk. Surpise me it let me do the migration.

    However, the RAID is still shown as RAID0:

    ------------------------------------------------------------------------
    Name      Resource  State       Description              Size
    ------------------------------------------------------------------------
    sissas0   FFFFFFFF  Available   PCIe x4 Planar 3Gb SAS Adapter

    hdisk5    00FF0000  Optimal     RAID 0 Array           387.9GB
     pdisk0   00030000  Active      SSD Array Member       387.9GB
     pdisk1   00000000  Active      SSD Array Member       387.9GB

    I am worrying about it because raid0 of two disks stripes across the two with no redundancy.

    What I need RAID1, a pure mirror, but IBM SAS RAID controller does not support RAID1.

    so what is exactly IBM RAID10 with only two disks?  RAID0 or RAID1?

    Any one knows for sure or Is there a way to verify it?

    Thanks!

    --Kang



    ------------------------------
    Kang Sun
    ------------------------------

    Original Message


  • 9.  RE: New SSD Drive shown as pdisk

    Posted Tue June 13, 2023 02:02 AM

    Since your RAID array size is the same as the individual SSDs, it would appear that the RAID array in question is a mirror aka RAID1.

    One way to verify this is to run command "getconf DISK_SIZE /dev/hdisk5" and divide the size reported getconf by 1024 in order to convert the size from megabytes to gigabytes. The sizes will not match exactly, but if the size is less than 400 gigabytes you most likely have mirror pair and if it is over 400 gigabytes then you have a stripe or concatenated pair of disks.

    Here is an example of a RAID10 array that has been created as mirror pair from the start.

    ------------------------------------------------------------------------
    Name      Resource  State       Description              Size
    ------------------------------------------------------------------------
    sissas0   FFFFFFFF  Available   PCIe3 x8 SAS RAID Internal Adapter 6Gb

    hdisk2    FC0200FF  Optimal     RAID 10 Array          387.8GB
     pdisk2   0002FFFF  Active      SSD Array Member       387.9GB
     pdisk3   0004FFFF  Active      SSD Array Member       387.9GB

    I'd power off the RAID adapter, which can be done by stopping the LPAR, which will cause the PCIe slots to be powered off, if and only if it is possible.

    FYI If you are in MDC the whole server will be powered off and if your are not in MDC but the "Power off when the last logical partition is shutdown" has been enabled, and this LPAR in question is the only/last LPAR running the physical server will be powered off. Both scenarios will lengthen downtime period.

    This article https://www.ibm.com/support/pages/manufacturing-default-configuration will explain what MDC is.



    ------------------------------
    Esa Kärkkäinen
    ------------------------------

    Original Message


  • 10.  RE: New SSD Drive shown as pdisk

    Posted Tue June 13, 2023 12:00 PM

    # getconf DISK_SIZE /dev/hdisk5
    369984

    Now I am much confident it is a mirror.

    Thanks! 

    --Kang



    ------------------------------
    Kang Sun
    ------------------------------

    Original Message