Drive Sparing

Question

Hi,

I have a query on VMAX drive sparing. Is permanent drive sparing gone now and Direct Member Sparing with rollback only as of 5876 Q4 2012 SR? If so is this true for all VMAX models? Does this not have an impact on performance if there are two rebuilds?

I looked at this paper and the permanet sparing is still present?

http://www.emc.com/collateral/hardware/white-papers/h6541-drive-sparing-symmetrix-vmax-wp.pdf

I may have got my wires crossed.

Thanks for your help

Victor

seancummins · Accepted Answer

Victor,

DMS rolls back so that spares aren't moving around to different physical locations in the array over time... this ensures that the spare coverage you have upon initial installation of the array remains the same throughout the lifespan of the array.

Thanks,

- Sean

seancummins · Answer

Direct Member Sparing is used in most cases, starting at 5876 Q4'12 SR, as you mentioned... it only falls back to permanent sparing for RAID6 14+2. Direct Member Sparing has less of a performance impact because we're proactively copying data directly from the failing drive, rather than taking the failing drive offline and performing a parity-based rebuild.

vforde · Answer

OK Sean thanks. So it is gone, just not sure why the spare needs to be rolled back out after the failed drive is replaced unless there is problems it not being recognised correctly as a data disk or something. I understand the VMAX can give the extra rebuild extra/v high task priority to counter any performance issues.

Thanks for your help

Victor

bhalilov1 · Answer

Sean Besides symdisk list -failed is there any way to see if there are sparing sessions going on ? (symcli)

VMAX

Drive Sparing

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