Hello Roger,
Tuesday, May 5, 2009, 9:07:22 PM, you wrote:
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Hello, Does it make any sense to use a bunch of 15K SAS drives as L2ARC cache for several TBs of SATA disks? For example: A STK2540 storage array with this configuration:
I was thinking about using disks from Tray 1 as L2ARC for Tray 2 and put all of these disks in one (1) zfs storage pool. This pool would be used mainly as astronomical images repository, shared via NFS over a Sun Fire X2200. Is it worth to do? -- |
I guess your files are astronomically big :)
But seriously - if your files are large and you expect to access them in large chunks sequentially then SATA drives can actually deliver same performance as your 15k SAS disks as you will be throughput bound. If it is the case than separating those 15ks as L2ARC probably doesn't make sense.
If you expect lots of writes and small random reads when a relatively large part of working set will fit into L2ARC then it might make a sense.
It also depends on how you configure your sata drives - for example you will usually get more benefit from L2ARC if your pools is raid-z[2] compared, except the case of a single-stream large I/O sequantial reader to raid-10.
In summary - it all depends on your workload...
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Best regards,
Robert Milkowski
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