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Migrating data to free up LDM RRS feed

  • Question

  • So, having 270 datasources, we seem to be at 2220 LDM entries according to the errlogs on one of our dpmservers.

    According to Ruud Baars script, 1120 LDM entries are volume extends.

    The LDM warning has appeared in the dpm console.

    since a third of the maximum LDM-value concists of extends/spanned volumes over five disks, id want to do some datamigration using MigrateDatasourceDataFromDPM to consolidate those volumes..

    I've got five SAN-attached disks in the pool at ~2TB each.

    I need to be certain that I can afford the temporarly higher LDM-value during the timeout (retention) for the old disks after migration, right? the rep. and rec.-volumes are migrated instantly but the old recoverypoint volumes will be retained for 7 days (short-term retention time for us)

    Also, are there any difference between using disk to disk migration contra migrating datasources to disk, except for control?

    Finally, say I migrate the first out of five disks to a newly created disk within the pool, will dpm include ALL volumes that are partially located on the sourcedisk, not only those that 'starts' on that sourcedisk but also those volumes that got expanded there (i.e those tiny 10GB volumes)

    since i have five disks to migrate, it seems that I have to multiple migrations on all disks in a row to get the LUNs smaller?

    The first source LUN is 2TB, got alot of spanned volumes, so the destination disk needs to be, say 3TB.

    When the first LUN has been migrated, the second source LUN has lost 1TB of spanned volumes, and only 1TB is neccessary for the destination LUN. with a tiny add-on overhead on the dest. LUN)

    Is this correct?


    Ivarson

    Friday, April 18, 2014 11:13 PM

All replies

  • Hi,

    Did you see Ruud Baars scipt: Space needed to migrate a disk script.   That will detail what data sources are on each disk(s) and how much space it will take to migrate each disk.  As noted, this assumes you only migrate one disk, wait for recovery points to expire, then re-run the script again to determine how much space another disk will need to migrate.   That is because some space on other disks may also be freed up if some data sources spanned disks.

    If you want to migrate individual data sources, then you can use that same script to see how much space is required for each individual data source.   DPM migrates both the replica and recovery point volume to the new disk(s) regardless of which method used.


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    Saturday, April 19, 2014 11:44 PM
    Moderator