Topic
1 reply Latest Post - ‏2014-04-28T20:11:28Z by AndersLorensen
robinsguk
robinsguk
31 Posts
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Pinned topic Preserving Easy Tier heat map during full system restore

‏2014-04-25T07:50:38Z |

Hello.

I'm migrating some LPARs on to a V7000 to a pool which has EasyTier enabled.

I've run some long running batch processes over a number days and the run times have reduced as expected as EasyTier has migrated the hot spots to my Solid State Drives (actually it's a LUN from Flash 820).

Next weekend we'll be going live and will be refreshing the entire LPAR from tape, a process which will take around 14 hours.

I'm concerned that the refresh will skew the EasyTier results causing my hot spots to be migrated back to SAS. Thiis would mean my first few batch runs will be slower until EasyTier has migrated the hot spots back to SSD/Flash.

1. Will the restore cause the currently migrated hot spots to be migrated back to SAS?

2. What would be the impact of me disabling EasyTier during the refresh process then enabling it again after the restores are complete? As long as the SSD?

3. Would EasyTier need to completely refresh its heat map if it was disabled and then enabled with a 24 hour period?

 

 

Thanks

Glenn

Updated on 2014-04-25T07:51:32Z at 2014-04-25T07:51:32Z by robinsguk
  • AndersLorensen
    AndersLorensen
    156 Posts
    ACCEPTED ANSWER

    Re: Preserving Easy Tier heat map during full system restore

    ‏2014-04-28T20:11:28Z  in response to robinsguk

    1. No. Sequential workloads are generally not counted toward defining hotspots. Mainly to avoid backups affecting it. Also sequential workloads does not bennifit alot from SSD's.

    2/3. I'm not 100% sure about this, but I'd expect the easytier to "forget" the heatmap of the volume, and start recording for 24 hours before starting to move anything around again, after you reactivate it.

    If the restore only takes 14 hours, I would not touch the V7000 at all. One big sequential restore will not affect the heat map at all. My biggest concern would be if the same Blocks would contain the same data after the restore, or if the heat map will be totally wrong.

     

    /Anders