> cache improve write performance or only reads?
L2ARC cache device is for reads... for write you want
Intent Log
The ZFS Intent Log (ZIL) satisfies POSIX requirements for
synchronous transactions. For instance, databases often
require their transactions to be on stable storage devices
when returning from a system call. NFS and other applica-
tions can also use fsync() to ensure data stability. By
default, the intent log is allocated from blocks within the
main pool. However, it might be possible to get better per-
formance using separate intent log devices such as NVRAM or
a dedicated disk. For example:
# zpool create pool c0d0 c1d0 log c2d0
Multiple log devices can also be specified, and they can be
mirrored. See the EXAMPLES section for an example of mirror-
ing multiple log devices.
Log devices can be added, replaced, attached, detached, and
imported and exported as part of the larger pool.
but don't underestimate the speed of several slow vdevs vs
one fast vdev.
> Does anyone make a 3.5" HDD format RAM disk system that isn't horribly
http://mail.opensolaris.org/pipermail/zfs-discuss/2007-July/041956.html
perhaps adding ram to the system would be more flexible?
Rob
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