0

Im assisting a customer which is stuck with a few old dell appliances.

The following scenario :

Dell PE R710 (4GB RAM, Windows Server 2008x64, Perc6i/6e, SAS4x) Dell PE 1950 (4GB RAM, Windows Server 2008x64, Perc6i/6e, SAS4x) Both have 2 Dell PowerVault MD1000x 15x1TB SAS discs@RAID5 pr DAS)

Ive tested with ATTO and im getting 1,5GB/s read performance on anything over 32KB pr block but the write performance is VERY different.. 450MB/s on the R710 but i get 38MB/s on the 1950..

Ive tried to do software raid on the 2 DAS'es on the 1950.. no help.. 50ish MB/s

  1. Could this be a hw fault? or maybe the raid is degraded? (customer doenst have any tools installed to check this..) I know they have never updated any firmware so i plan do use the server update tool to update all and redo tests..
  2. Would 2xDAS@RAID5 through the Perc6/e controller and then software stripe ontop be faster than a 2xDAS@RAID6 HW striped (RAID60) ?? Sequential write performance is the only thing they need since this will be a dump station.
  3. If we were to replace the aging 1TB SAS drives with cheaper NAS ready 4TB SATA drives, would this work on the newest fw for the md1000 and anyone got some experience with the stability ? Any reccomendations on a drive?

Any tips are apriciated

br Thor

5
  • Do you have OMSA installed to manage the configuration on the PERC cards? Typically write performance is better than read performance if write-back cache is enabled. Without caching, you have a RAID5 write penalty to deal with when writing directly to the disks. Please update with details of the PERC settings if possible!
    – JimNim
    Mar 30, 2015 at 13:45
  • hi! They were all setup to writeback cache. But still with writethrough, 30-40MB/s is way below my expected performance...
    – TEB
    Mar 31, 2015 at 12:03
  • 2
    Check the battery backup isn't disconnected/failed on the slow PERC controller, it may automatically disable writeback mode.
    – James Yale
    Mar 31, 2015 at 12:36
  • James Yale: How do i check this? Through the Open Manage Tools ? Or is there are a warning light/sensor of sorts?
    – TEB
    Mar 31, 2015 at 18:16
  • @TEB OMSA will tell you - if the battery has failed and not just disconnected then you should get front panel warning lights.
    – Zypher
    Mar 31, 2015 at 18:57

0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.