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Below is our current server configuration. In a few weeks I will be simulating a disaster recovery by installing 7 new disks (1 hot spare) and restoring all VMs from the backups.

Will I gain anything by changing the RAID stripe size to something other than 64KB? The RAID controller has options for 8KB, 16KB, 32KB, 64KB, 128KB, 256KB, 512KB, 1MB.

Any recommendations based on the specification below would be greatly appreciated - thanks.

Hardware:

Dell R630
Dell H730P Mini Raid Controller
2XE5-2670 V3
512GB RAM
12G 1.8TB 10K SAS Disk

    Software:

   Vmware ESX 6.7 U3

    Configuration:

    RAID 10, 128k Stripe Size
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Generally speaking, selecting a stripe size is a bandwidth vs IOPs tradeoff: smaller stripe size often means higher sequential read/write speed, while bigger stripe size means higher concurrent IOPs (due to less IO spanning multiple disks).

That said, mechanical HDD are highly unbalanced devices: latency dominates until relatively big IO (>= 32 KB) are issued, so stripe element size (or chunk size, in Linux MDRAID parlance) under 64 KB are rarely used (which happens to be the default value).

For a virtualization host, where IOPs are far more important than single-thread sequential speed, I would increase it to 256 KB.

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  • The other thing that comes into play here is the read and write cache on the drive or set of drives and that of the RAID controller you may be better off with a larger stripe size if it fits Within the cache size of the drives. Of course if you don't have a battery backed up cache on the controller, then doing cache disabled writes (write through) will slow performance but increase stability. – Rowan Hawkins Mar 26 '20 at 20:11
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From the H730 manual:

The default and recommended stripe element size is 64 KB. A larger stripe element size provides better read performance if your system mostly does sequential reads.

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  • we want to use the server for virtualization. – Ferdi KUCUK Mar 23 '20 at 19:38
  • @shodanshok; @bert; Thank you very much. – Ferdi KUCUK Mar 26 '20 at 22:49

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