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Proper way to create/restore mksysb with Powerpath

  • 1.  Proper way to create/restore mksysb with Powerpath

    Posted Wed June 11, 2025 08:22 AM

    I hate Powerpath, but I'm stuck with it at this site.   That said, does anyone have the proper procedure to an AIX 7.3 mksysb when the disks are utilizing Powerpath.

    I tried this method:

    pprootdev off
    mksysb -ie /my_mount_point
    pprootdev on

    But that turned into a whole day headache before finally getting the mksysb reloaded on my test server (I'll spare the details)

    I asked Dell (EMC support) and they sent me a pdf dated March 2024 called Dell Technologies Host Connectivity Guide for IBM AIX,  yet it's referencing AIX 4.3!!!

    I did inform Dell that AIX 4.3 was released in October 1997 and went out of support in 2006.  Since then, AIX 5.1, 5.2, 6.1, 7.1, 7.2, and 7.3 have come out and they need new tech writers.   lol.

    Thanks.



    ------------------------------
    Gary Gorski
    ------------------------------


  • 2.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 12:40 AM

    Hi Gary,

    This IBM support article mentions running pprootdev fix before any command that performs a bosboot, such as mksysb. Read through and see if it helps. 



    ------------------------------
    Zaki Jääskeläinen
    ------------------------------

    Original Message


  • 3.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 02:47 AM

    I recall that the initial setup for an AIX machine doing SAN boot using PowerPath is to do the LUN mapping and zoning so that only a single path is visible to AIX. After installing and configuring PowerPath you update the LUN mapping and zoning to expose the remaining paths.

    I expect this to be the case also when restoring a mksysb (in addition to the extra steps taken during the backup).



    ------------------------------
    Zaki Jääskeläinen
    ------------------------------

    Original Message


  • 4.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 03:58 PM

    Hi Gary...

     

    My experience restoring mksysb to an LPAR using a DELL SAN storage and using PowerPath is using a NIM Server...

    When LPAR booted and mksysb restore procedure attempts to create the new rootvg volume group an error message is displayed indicating that there are too many disks with the same PVID and that the Volume Group cannot be created. (LED code 0544 may be displayed)

    This is because mkvg command does not recognize the usual pseudo-drive hdiskpower (obviously due Powerpath driver is not loaded and running at that time), it only detects a few standard hdisk devices, one for each available paths through the selected LUN.

    The procedure will prompt you to correct the problem manually and then continue.

     

    In order to mksysb can be created and continue with the data restoration, you must first delete the hdisk devices that have all the paths to the LUN except one.

    You will notice It can't be done with rmdev command because it fails to discard the device because it is busy. You must delete the hdisk devices from the temporary ODM.

    You may use the following script to delete the information.

     

                 # lspv                (will show you many hdisks with the same PVID)

                 # cd /etc/objrepos

                 # for i in $(ls Cu*)                                                             (run this for each DUP hdisk except one) – old AIX levels need you specify all the Cu files manually

                    do

                               odmdelete -o $i -q name=hdiskXX                           (where hdiskXX is the name of hdisk you want to delete)      

                    done

                 # lspv                (will show you there is only one hdisk with a unique PVID to use)

     

    After this you can continue restoring mksysb.

    Near the end, the mksysb restore procedure will attempt to create a boot image over the hdisk.

    Again the procedure will be interrupted because bosboot will not be able to create boot image due many duplicated disks (the procedure recognize again the removed hdisks because a cfgmgr was run on the fly)... you must again manually remove the hdisks with duplicated PVID, but this time keep in mind that bosboot attempts to create that boot image on a specific hdisks (you can't just delete all except one) It is important to remove all but the one bosboot intends to use.

     

    Note:   EMC (DELL) storage systems use one of those paths as the "active" connection. With something like a PowerPath driver, paths balancing and switching from path to path will not occurr, so only one of those hdisks will be the right, usually the one associated with ipldevice device (check /dev directory)

     

    Important:       After delete unwanted hdisks devices, you must create the boot image manually and not return to the restore procedure, as the bosboot command will not be run again. Therefore, even if the problem not longer exists, boot image will not be created. Run # bosboot -ad /dev/hdiskXX on the left hdisk to create boot image yourself and then continue.

     

    I hope I can help you or give you some guidance.

     

    Regards

     

    Luis A. Rojas Kramer

     




    Original Message


  • 5.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 05:03 PM

    I like this way, too.  See my resolution which is similar to this.   Thx.



    ------------------------------
    Gary Gorski
    ------------------------------

    Original Message


  • 6.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 02:39 AM

    I understand your frustration about Powerpath and its old documentation ;-).

    Did you encounter a lot of LED 554 during boot, when you were attempting to boot from your mksysb?



    ------------------------------
    Richard Westerik
    Principal engineer
    Simac IT NL bv
    Ede
    +31651575123
    ------------------------------

    Original Message


  • 7.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 03:44 AM

    You might also consider scenario when you restore mksysb to lv/vscsi backed disk. It will allow you to omit single path issue and skip part of setting proper zoning/lun masking (especially if other team is taking care of SAN network). After successful restore it would require to migrate rootvg via mirroring as additional step, but it still might be more convenient then direct restore on EMC backed disk. 

    J. 



    ------------------------------
    Jakub Pacowski
    ------------------------------

    Original Message


  • 8.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Thu June 12, 2025 05:00 PM

    Thanks for the responses.   I have info and a workaround.

    What works

    On the lpar:
    pprootdev fix
    mksysb -ie /mount_point
    pprootdev fixback

    Note:  use pprootdev off/on when cloning to spare disk, but use pprootdev fix/pprootdev fixback when doing a mksysb

    During the NIM load, 

    3 Start Maintenance Mode for System Recovery
      1 Access a Root Volume Group

    It should list four disks.

      2) Access this Volume Group and start a shell before mounting filesystems

    Do this:

    # for disk in hdisk0 hdisk2 hdisk4 hdisk6
    > do
    > dd if=/dev/zero of=/dev/$disk bs=512 count=1000

    > done

    Exit.

    The mksysb will load and powerpath will be enabled when it comes up.

    NOTE:  You will have to know your PVID's, if you have both a rootvg and old_rootvg/altinst_rootvg



    What does NOT work:

    Changing your HMC profile to boot up on only one fiber path

    Pulling the bosinst.data and image.data from the mksysb, removing three of the four disk stanzas, and then defining that bosinst_data as a resource to use with mksysb.

    These procedures don't work either:

    https://www.dell.com/support/kbdoc/en-us/000219423/mksysb-restore-fails-with-error-0301-165-bosboot-failed  

    https://www.ibm.com/support/pages/mksysb-restore-fails-error-0301-165-bosboot-failed

    Thanks all.  I have my workaround.



    ------------------------------
    Gary Gorski
    ------------------------------

    Original Message


  • 9.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Fri June 13, 2025 04:32 AM

    It's been many years since I worked in an environment where PowerPath is in use.  But reading about all this extra complication to restore a mksysb reinforces the decision that we made when starting to implement NPIV to keep rootvg on VSCSI and only use NPIV for data LUNs.



    ------------------------------
    Phill Rowbottom
    Unix Consultant
    Service Express
    Bedford
    ------------------------------

    Original Message


  • 10.  RE: Proper way to create/restore mksysb with Powerpath

    Posted Mon June 16, 2025 01:59 PM

    A customer of mine complained to EMC (DELL) because some of their LPARs couldn't boot (LED 0544) from SAN LUNs (interestingly, not all of them)

    From EMC Storage's perspective the LPARs could access any of their configured paths without issue.

    They argued that there might be an issue with the operating system, as they didn't find any problems with the PowerPath driver.

    After a brief bounce they agreed to install a hotfix package. This temporally fix the problem, but over time, and randomly the problem reappeared.

     

    There seems to be no reliable way to get PowerPath to boot properly. Therefore, it would be better to use rootvg on vSCSI disks.

     

    Luis A. Rojas Kramer

     




    Original Message


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