Quoting Terje Elde <te...@elde.net>:
On 16. sep. 2011, at 12:31, free...@top-consulting.net wrote:
Right now I defined an entire array of 8TB ( all 16 disks )
separated in two pieces. 50 GB for FreeBSD to boot and the rest
available to configure as storage.
ZFS will want to write to it's ZIL (zfs intent log) before writing
to the final location of the data. Even if you're not waiting for
the ZIL-write to disk (because of the controller ram), those writes
will probably make it through to disk. That gives you twice as many
writes to disk, and a lot more seek.
If you want to take zfs for a proper spin, I'd like to sugget adding
two small SSDs to the setup, mirrored by zfs. You can use those both
for the ZIL, and also as cache, for the array. That's a fairly small
investment these days, and I would be surprised if it didn't
significantly improve performance, both for your benchmark, and real
load.
Note: you might be in trouble if you loose your ZIL, thus the
doubling up. I *think* you can SSD a cache without risking dataloss,
but don't take my word for it.
Terje
I know it's usually a big no-no but since I have the battery backed-up
write cache from the raid card, can't I just disable the ZIL entirely ?
_______________________________________________
freebsd-questions@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
