James Lever wrote:
On 04/07/2009, at 3:08 AM, Bob Friesenhahn wrote:
It seems like you may have selected the wrong SSD product to use.
There seems to be a huge variation in performance (and cost) with
so-called "enterprise" SSDs. SSDs with capacitor-backed write caches
seem to be fastest.
Do you have any methods to "correctly" measure the performance of an
SSD for the purpose of a slog and any information on others (other
than anecdotal evidence)?
First, determine the ZIL pattern for your workload using zilstat.
Then buy an SSD which efficiently handles a sequential workload
which is similar to your workload. For example, if your workload
creates a lot of small ZIL iops, then you'll want to favor SSDs which
have high, small, write iop performance.
-- richard
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