On Tue, 20 Oct 2009, Scott Meilicke wrote:
A. Use all 32G for the ZIL
B. Use 8G for the ZIL, 24G for an L2ARC. Any issues with slicing up an SSD like
C. Use 8G for the ZIL, 16G for an L2ARC, and reserve 8G to be used as a ZIL for
the future zpool.
Since my future zpool would just be used as a backup to disk target,
I am leaning towards option C. Any gotchas I should be aware of?
Option "A" seems better to me. The reason why it seems better is that
any write to the device consumes write IOPS and the X25-E does not
really have that many to go around. FLASH SSDs don't really handle
writes all that well due to the need to erase larger blocks than are
actually written. Contention for access will simply make matters
worse. With its write cache disabled (which you should do since the
X25-E's write cache is volatile), the X25-E has been found to offer a
bit more than 1000 write IOPS. With 16GB of RAM, you should not need
a L2ARC for a backup to disk target (a write-mostly application).
The ZFS ARC will be able to expand to 14GB or so, which is quite a lot
of read caching already.
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