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SystemAdmin
SystemAdmin
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Pinned topic x3500/ServeRAID Mixed SAS drive speeds

‏2013-02-13T23:13:36Z |
Hi

All the currently available disks for the x3500 have a rated I/O thoughput of 6Gbps from a mix of 7.2K,10K and 15K rpm disks. Classic good practice advises against mixing different drive speeds (rpm) in an single array due to latency of the slower drives.

There is nothing in the configurators to suggest that the above is not supported but in the x3500 User Guide there is the statement:

"All hot-swap drives in the server must have the same throughput speed rating; using drives with different speed ratings might cause all drives to operate at the speed of the slowest drive."

http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=migr-5089504

Unfortunately the advice in the Installation & User Guide is ambiguous as drives with different speeds (7.2k,10K,15K rpm) all have the same throughput (6Gbps).

So the question is: In the case of the x3500 I intend to use a ServeRAID 5100 and have 2 separate arrays. 2x 300GB 10Krpm in RAID 1, 4x 1TB 7.2Krpm in RAID 5. Bearing in mind the arrays will always be separate, is it supported to mix the drives as above in the internal enclosure?