On Thu, Dec 23 at 11:25, Stephan Budach wrote:
Hi,
as I have learned from the discussion about which SSD to use as ZIL
drives, I stumbled across this article, that discusses short stroking for
increasing IOPs on SAS and SATA drives:
[1]http://www.tomshardware.com/reviews/short-stroking-hdd,2157.html
Now, I am wondering if using a mirror of such 15k SAS drives would be a
good-enough fit for a ZIL on a zpool that is mainly used for file services
via AFP and SMB.
I'd particulary like to know, if someone has already used such a solution
and how it has worked out.
Haven't personally used it, but the worst case steady-state IOPS of
the Vertex2 EX, from the DDRDrive presentation, is 6k IOPS assuming a
full-pack random workload.
To achieve that through SAS disks in the same workload, you'll
probably spend significantly more money and it will consume a LOT more
space and power.
According to that Tom's article, a typical 15k SAS enterprise drive is
in the 600 IOPS ballpark when short-stroked and consumes about 15W
active. Thus you're going to need ten of these devices, to equal the
"degraded" steady-state IOPS of an SSD. I just don't think the math
works out. At that point, you're probably better-off not having a
dedicated ZIL, instead of burning 10 slots and 150W.
--eric
--
Eric D. Mudama
edmud...@mail.bounceswoosh.org
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