Re: append-only file

From: Lamar Saxon (Lamar.Saxon_at_AMERICREDIT.COM)
Date: 12/10/04

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    Date:         Fri, 10 Dec 2004 14:36:55 -0600
To: aix-l@Princeton.EDU

    Have you looked in to converting to a BIG VG with the chvg command ?

    Look specifically at man page for chvg and the:

    -B Changes the volume group to big vg format. This can accommodate up to
    128
    physical volumes and 512 logical volumes.

       Notes:

         1. The -B flag cannot be used if there are any stale physical
    partitions
            or there are any open logical volumes in the volume group.
         2. Once the volume group is converted, it cannot be imported into
    AIX
            4.3.1 or lower versions.
         3. The -B flag cannot be used if the volume group is varied on in
            concurrent mode.
         4. There must be enough free partitions available on each physical
    volume
            for the VGDA expansion for this operation to be successful.
         5. Since the VGDA resides on the edge of the disk and it requires
            contiguous space for expansion, the free partitions are required
    on the
            edge of the disk. If those partitions are allocated for user
    usage,
            they will be migrated to other free partitions on the same disk.
    The
            rest of the physical partitions will be renumbered to reflect
    the loss
            of the partitions for VGDA usage. This will change the mappings
    of the
            logical to physical partitions in all the PVs of this VG. If you
    have
            saved the mappings of the LVs for a potential recovery
    operation, you
            should generate the maps again after the completion of the
    conversion
            operation. Also, if the backup of the VG is taken with the map
    option
            and you plan to restore using those maps, the restore operation
    may
            fail since the partition number may no longer exist (due to
    reduction).
            It is recommended that backup is taken before the conversion,
    and right
            after the conversion if the map option is utilized. Since the
    VGDA
            space has been increased substantially, every VGDA update
    operation
            (creating an LV, changing an LV, adding a PV, and so forth) may
    have a
            considerably longer duration.
         6. A big VG only supports Enhanced Concurrent Capable.

    Be aware there was an issue with the chvg command and AIX 5.2...

    HTH,
    Lamar

    Also, the big VG is supported when you create the volume group too.

    mkvg -B for big
    mkvg -G for giant

            -----Original Message-----
            From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On
    Behalf Of cbaker@GOODYEAR.COM
            Sent: Friday, December 10, 2004 1:58 PM
            To: aix-l@Princeton.EDU
            Subject: Re: append-only file
            Importance: High


            Folks,

            We have a two P655s running AIX 5.1 ML 04. Each has 3 or 4
    volume groups on them that are using EMC Clariion SAN disks. Each VG is
    about 1 to 1.5 TB big. They are made up of hdisks (hdiskpowers) LUNS
    that are about 50 GB each. We wanted to add disks to each of these VGs
    and, maybe, add a VG to each P655.

            Our EMC team presented us with new LUNs that are about 120 GB
    each. We thought this would be better since we are hitting the 32 PV
    limit on some of the VGs we now have.

            When we tried to add one of these new hdiskpowers to a VG that
    has 26 PV's already, it gave this error:

            Command: failed stdout: yes stderr: no

            Before command completion, additional instructions may appear
    below.

            0516-1162 extendvg: Warning, The Physical Partition Size of 64
    requires the
                    creation of 2157 partitions for hdiskpower184. The
    limitation for volume group
                    nfs4vg1 is 1016 physical partitions per physical volume.
    Use chvg command
                    with -t option to attempt to change the maximum Physical
    Partitions per
                    Physical volume for this volume group.
            0516-792 extendvg: Unable to extend volume group.



            When we tied to change the VG with the command "chvg -t 3
    nfs4vg1", we got this error

    > chvg -t 3 nfs4vg1
            0516-1193 chvg: WARNING, once this operation is completed,
    volume group nfs4vg1
                    cannot be imported into AIX 430 or lower versions.
    Continue (y/n) ? y
            0516-1160 lchangevg: Volume group conversion is not possible
    since the factor value
                    of 3 can accommodate utmost 10 physical volumes.
            0516-732 chvg: Unable to change volume group nfs4vg1.



            Here is what "lsvg nfs4vg1" shows:


            VOLUME GROUP: nfs4vg1 VG IDENTIFIER:
    00201b1a00004c00000000f
            5d653ad2a
            VG STATE: active PP SIZE: 64
    megabyte(s)
            VG PERMISSION: read/write TOTAL PPs: 19016
    (1217024 megabyte
            s)
            MAX LVs: 256 FREE PPs: 1024
    (65536 megabytes)
            LVs: 8 USED PPs: 17992
    (1151488 megabyte
            s)
            OPEN LVs: 8 QUORUM: 1
            TOTAL PVs: 26 VG DESCRIPTORS: 26
            STALE PVs: 0 STALE PPs: 0
            ACTIVE PVs: 26 AUTO ON: yes
            MAX PPs per PV: 1016 MAX PVs: 32
            LTG size: 128 kilobyte(s) AUTO SYNC: no
            HOT SPARE: no



            What are our options here?

            Was hopping to move larger disks (LUNs / hdiskpowers) into each
    VG and then migrate data over so that I could slowly remove the smaller
    disks, but now I am not so sure that will be as easy as I thought.

            Is part of the problem because these two servers are still on
    AIX 5.1 rather than AIX 5.2? Does 5.2 allow you more than 32 PV in a
    VG?

            If I make new VG's with the new larger disks 1) What should I
    be mindful of? 2) Can I then easily move / migrate the contents of
    each of these 64 MB PP VG to these newer 256 MB PP VG's?

            Thanks in advance for any input you can offer.

            Sincerely,





            Christopher M. Baker
            Senior Technical Support Analyst
            DSE/TCO
            Goodyear Tire and Rubber Company

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