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  • 1.  migratepv duration

    Posted Wed May 26, 2010 10:13 AM

    Originally posted by: usrb


    Hi2all!

    I need a quick answer from someone experienced with migratepv command and SAN disks.
    How long aprox does it take to migrate lv to another disk?
    I know this is hard to answer without exact facts, but what can I expect, 20/50/100 MB/s?
    Application will be powered off so no read/writes will happen.

    Thanks
    #AIX-Forum


  • 2.  Re: migratepv duration

    Posted Wed May 26, 2010 12:17 PM

    Originally posted by: SystemAdmin


    quick answer: depends.

    (on pp size, hbas, switches, storage system(s)...)
    why not test with a small ad hoc created lv?
    #AIX-Forum


  • 3.  Re: migratepv duration

    Posted Thu May 27, 2010 12:00 AM

    Originally posted by: j.gann


    like Delgado writes, it very much depends. also consider lvm mirrors are synchronous. I often see cross site mirror writes having only as low as 50-70% of same-site disk writes because of bandwith loss on the site-interconnect network. (the "slowest" disk in a mirror determines the overall mirror write throughput).

    take with grains of salt:

    lowend storage: 60-80 Mbyte/s
    highend storage: 100-250 Mbyte/s

    Joachim
    #AIX-Forum


  • 4.  Re: migratepv duration

    Posted Thu May 27, 2010 07:52 AM

    Originally posted by: usrb


    Ok, thanks guys
    #AIX-Forum


  • 5.  Re: migratepv duration

    Posted Thu May 27, 2010 06:56 PM

    Originally posted by: esv


    the whole concept of LVM is that you are able to perform this task w/o downtime given that the disks are on the same volume group.

    regards,
    esv.
    #AIX-Forum


  • 6.  Re: migratepv duration

    Posted Sun May 30, 2010 06:53 AM

    Originally posted by: niella


    Hi,

    Perhaps consider the use of mklvcopy based mirroring and then break the mirror afterwards. It adds an extra step but using 'syncvg' has the benefit of parallel synchronization to speed up the migration:

    From man syncvg:
    -P NumParallelLps
    Numbers of logical partitions to be synchronized in parallel. The valid range for NumParallelLps is 1 to 32. NumParallelLps
    must be tailored to the machine, disks in the volume group, system resources, and volume group mode.

    When a volume group is varied on in concurrent mode, all other cluster nodes that have this volume group varied must be at
    least AIX 4.3.0, otherwise syncvg will ignore this option and continue. Note: See Description above for more information.

    Depending on how much you are prepared to strain the SAN, you could do:
    1. mklvcopy LVName 2 TargetPV
    2. syncvg -l LVName -P 32
    3. rmlvcopy LVName 1 SourcePV

    Regards,
    Niel
    #AIX-Forum


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