On Fri, 3 Aug 2012, Neil Perrin wrote:

For the slog, you should look for a SLC technology SSD which saves unwritten data on power failure. In Intel-speak, this is called "Enhanced Power Loss Data Protection". I am not running across any Intel SSDs which claim to match these requirements.

- That shouldn't be necessary. ZFS flushes the write cache for any device written before returning
from the synchronous request to ensure data stability.

Yes, but the problem is that the write IOPS go way way down (and device lifetime suffers) if the device is not able to perform write caching. A consumer-grade device advertizing 70K write IOPS is definitely not going to offer anything like that if it actually flushes its cache when requested. A device with a reserve of energy sufficient to write its cache to backing FLASH on power fail will be able to defer cache flush requests.

Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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