grant lowe wrote:
Ok. I blew it. I didn't add enough information. Here's some more detail:

Disk array is a RAMSAN array, with RAID6 and 8K stripes. I'm measuring performance with the results of the bonnie++ output and comparing with with the the zpool iostat output. It's with the zpool iostat I'm not seeing a lot of writes.

Since ZFS never writes data back where it was, it can coalesce multiple outstanding writes into fewer device writes. This may be what you're seeing. I have a ZFS IOPs demo where the (multi-threaded) application is performing over 10,000 synchronous write IOPs, but the underlying devices are only performing about 1/10th of that, due to ZFS coalescing multiple outstanding writes.

Sorry, I'm not familiar with what type of load bonnie generates.

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