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June 3rd, 2014 08:00
Hot Spare
If we have 4+1 R5 600GB, one disk fails.... Data on R5 is 200GB. We have two host spares 300GB and 600GB with the same RPM. Which drive will be picked as a hot spare for 600GB drive?
I believe it will use 600GB. Can you confirm?
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Rainer_EMC
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June 3rd, 2014 09:00
See the McX white paper – it explains hot spare selection
But maybe some more basic RAID 101 – a smaller hot spare drive cannot spare for a larger data drive
RRAO1
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June 3rd, 2014 09:00
So 600GB is correct then. It does not matter how much data is on the LUNs.
RRAO1
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June 3rd, 2014 10:00
Excellent. Thank you for confirming.
Regards,
Ramesh Rao
Storage Solutions Architect
ShoreGroup, Inc.
+1 (201) 344-2511
AdamFox
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June 3rd, 2014 10:00
Correct. The amount of data in the LUN doesn't matter. The issue is that you would have stripes on the 600GB drives that would not exist on the 300GB drive. So that means you can't complete the stripe, thus you cannot rebuild. Best practice for sparing is 1 spare per 30 drives of each type (where type is technology, speed, and capacity). If you keep to that, you will stay out of trouble.