Erik Trimble wrote:
So SSDs for ZIL/L2ARC don't bring that much when used with raidz2/raidz3,
if I write a lot, at least, and don't access the cache very much,
according
to some recent posts on this list.
Not true.
Remember: ZIL = write cache
ZIL is NOT a write cache. The ZIL is the Intent Log not a cache. It is
used only for synchronous writes. It is not a cache because the term
"cache" implies the data is also somewhere else and you lose nothing but
potential performance if you loose the cache.
ZFS calls the devices used to hold the ZIL (there is one ZIL per
dataset) a SLOG (Separate Log device).
Note also the recent addition of the "logbias" dataset property.
--
Darren J Moffat
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