Change rootvg hdisk numbers? - Aix

This is a discussion on Change rootvg hdisk numbers? - Aix ; Hello World, What with disks breaking, SCSI buses ceasing work, SSA disks being replaced and other disk-related "events", my hdisk number assignments are in a bit of a hash. My SCSI rootvg disks low live at hdisk15 and hdisk23, while ...

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  1. Change rootvg hdisk numbers?

    Hello World,

    What with disks breaking, SCSI buses ceasing work, SSA disks being
    replaced and other disk-related "events", my hdisk number assignments
    are in a bit of a hash. My SCSI rootvg disks low live at hdisk15 and
    hdisk23, while hdisk0 and 1 are SSA disks. Now I know that this doesn't
    actually affect operations, but it looks damn untidy.

    Since I'm taking the machine down this Saturday, I thought I'd tidy up
    a bit. What I intend to do is rmdev everything down from the SSA
    adapters and run a cfgmgr. That should restore some semblance of order.
    However, that doesn't fix my rootvg disks, which I cannot rmdev, of
    course, while the machine is running. Does anyone know of a way that
    will restore my SCSI disks to hdisk0 and hdisk1 as the SCSI gods
    intended?

    Thanks in advance,
    Menno Willemse


  2. Re: Change rootvg hdisk numbers?


    Menno Willemse wrote:
    > Hello World,
    >
    > What with disks breaking, SCSI buses ceasing work, SSA disks being
    > replaced and other disk-related "events", my hdisk number assignments
    > are in a bit of a hash. My SCSI rootvg disks low live at hdisk15 and
    > hdisk23, while hdisk0 and 1 are SSA disks. Now I know that this doesn't
    > actually affect operations, but it looks damn untidy.
    >
    > Since I'm taking the machine down this Saturday, I thought I'd tidy up
    > a bit. What I intend to do is rmdev everything down from the SSA
    > adapters and run a cfgmgr. That should restore some semblance of order.
    > However, that doesn't fix my rootvg disks, which I cannot rmdev, of
    > course, while the machine is running. Does anyone know of a way that
    > will restore my SCSI disks to hdisk0 and hdisk1 as the SCSI gods
    > intended?
    >
    > Thanks in advance,
    > Menno Willemse


    assuming that hdisk0 and hdisk1 are mirrored disks, unmirror, rmdev the
    empty disk, cfgmgr to recreate that disk as hdisk0, remirror and repeat.


  3. Re: Change rootvg hdisk numbers?


    Menno Willemse wrote:
    > Hello World,
    >
    > What with disks breaking, SCSI buses ceasing work, SSA disks being
    > replaced and other disk-related "events", my hdisk number assignments
    > are in a bit of a hash. My SCSI rootvg disks low live at hdisk15 and
    > hdisk23, while hdisk0 and 1 are SSA disks. Now I know that this doesn't
    > actually affect operations, but it looks damn untidy.
    >
    > Since I'm taking the machine down this Saturday, I thought I'd tidy up
    > a bit. What I intend to do is rmdev everything down from the SSA
    > adapters and run a cfgmgr. That should restore some semblance of order.
    > However, that doesn't fix my rootvg disks, which I cannot rmdev, of
    > course, while the machine is running. Does anyone know of a way that
    > will restore my SCSI disks to hdisk0 and hdisk1 as the SCSI gods
    > intended?
    >


    If you can get hdisk0 and hdisk1 free AND ( rootvg is mirrored OR you
    have a 3rd disk for rootvg )


    0) umount all fs from your SSA system and exportvg any vg on your ssa
    devices
    1) remove hdisk0 and hdisk1 device entries
    ( BTW: I do not know how to recreate hdisk from a SSA device or even
    raid )

    2) DO NOT run cfgmgr
    3) create dummy devices named hdisk0 and hdisk1
    - Keeps off cfgmgr to use these names
    - Howto: serach this group for ( mkdev dummy hdisk )
    4) Reconfigure your SSA disk to what ever hdisk name. Maybe a simple
    cfgmgr is enough.
    5) break your mirror to free hdisk15 and remove the device entry for
    the freed disk
    - rmdev -l hdisk23 -d
    6) remove the hdisk0 dummy device entry
    - rmdev -l -d hdisk0
    7) run cfgmgr - the free disk should be now hdisk0
    8) remirror your rootvg with that disk ( update bootlist )
    9) after you have no stale partitions - unmirror to free the hdisk23
    repeat steps 6 to 8 for hdisk1/hdisk23
    10) reboot to verify

    be happy
    Hajo


  4. Re: Change rootvg hdisk numbers?

    Hi Folks,

    Good tips all. Thanks! Especially creating the hdisk0 and hdisk1
    placeholders. In fact, I'll do that now as the SSA hdisk0 and 1 are not
    used.

    Oh, did I mention that tomorrow is "nimadm" day? Wish me luck!

    Cheers,
    Menno


  5. Re: Change rootvg hdisk numbers?

    Menno Willemse wrote:
    ...
    > Oh, did I mention that tomorrow is "nimadm" day? Wish me luck!

    My wishes are with you. But what the ... is a "nimadm" day ?

    regards
    Hajo


  6. Re: Change rootvg hdisk numbers?

    Why go to all this trouble, when you can simply do (assuming that
    hdisk0 and 1 are free):

    chdev -P -l hdisk7 (or whatever the disk is) -a name=hdisk0

    -P will actually only change it in the ODM and then you can reboot and
    all will be fine.


  7. Re: Change rootvg hdisk numbers?


    tacho wrote:
    > Why go to all this trouble, when you can simply do (assuming that
    > hdisk0 and 1 are free):
    >
    > chdev -P -l hdisk7 (or whatever the disk is) -a name=hdisk0
    >
    > -P will actually only change it in the ODM and then you can reboot and
    > all will be fine.


    Nice to know but it requries a reboot which is not nessessary in the
    early post - even if i mentioned it.
    So if somebody goes for a reboot then your solution is really better
    but the change of the bootlist should not be forgotten.

    regards
    Hajo


  8. Re: Change rootvg hdisk numbers?

    Hajo Ehlers a écrit :
    > tacho wrote:
    >> Why go to all this trouble, when you can simply do (assuming that
    >> hdisk0 and 1 are free):
    >>
    >> chdev -P -l hdisk7 (or whatever the disk is) -a name=hdisk0
    >>
    >> -P will actually only change it in the ODM and then you can reboot and
    >> all will be fine.

    >
    > Nice to know but it requries a reboot which is not nessessary in the
    > early post - even if i mentioned it.
    > So if somebody goes for a reboot then your solution is really better
    > but the change of the bootlist should not be forgotten.
    >
    > regards
    > Hajo
    >


    Don't we need a savebase to update the ODM extract saved in the boot
    image, as this disk is in rootvg ?

    Nicolas.

  9. Re: Change rootvg hdisk numbers?


    Hajo Ehlers wrote:

    > > chdev -P -l hdisk7 (or whatever the disk is) -a name=hdisk0


    > Nice to know but it requries a reboot which is not nessessary in the
    > early post - even if i mentioned it.
    > So if somebody goes for a reboot then your solution is really better
    > but the change of the bootlist should not be forgotten.
    >


    yes, for sure, but he said that he will be doing a reboot anyway.
    and the bootlist is of course also necessary.
    (but even if he forgets, he can do it from the SMS also)


  10. Re: Change rootvg hdisk numbers?

    Hello World,

    tacho wrote:
    > Hajo Ehlers wrote:
    >
    > > > chdev -P -l hdisk7 (or whatever the disk is) -a name=hdisk0

    >
    > > Nice to know but it requries a reboot which is not nessessary in the
    > > early post - even if i mentioned it.
    > > So if somebody goes for a reboot then your solution is really better
    > > but the change of the bootlist should not be forgotten.
    > >

    >
    > yes, for sure, but he said that he will be doing a reboot anyway.
    > and the bootlist is of course also necessary.
    > (but even if he forgets, he can do it from the SMS also)


    Well, I'm pleased to say that it did work, and I didn't have to reboot.
    (people here are jumpy about reboots). Nimadm day was the day when I
    upgraded the systems to AIX 5.2. This went relatively well except that
    a telnet problem showed up - took me a while to find out what it was,
    and for someone to find a workaround.

    Tomorrow I put back HACMP, and all will be no worse than it was before.

    Cheers,
    Menno


  11. Re: Change rootvg hdisk numbers?

    On 2006-11-10, Menno Willemse wrote:

    > Well, I'm pleased to say that it did work, and I didn't have to reboot.
    > (people here are jumpy about reboots).


    Is that because they like to play "find out which of the many changes causes
    the system to not boot"? Fun game: the longer the uptime, and the more changes
    done to the system during that uptime, the higher your score.

    Bonus points are given when you get to play in production hours.

    --
    Jurjen Oskam

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