On 11/14/12 03:24, Sašo Kiselkov wrote:
On 11/14/2012 11:14 AM, Michel Jansens wrote:
Hi,
I've ordered a new server with:
- 4x600GB Toshiba 10K SAS2 Disks
- 2x100GB OCZ DENEVA 2R SYNC eMLC SATA (no expander so I hope no
SAS/SATA problems). Specs:
http://www.oczenterprise.com/ssd-products/deneva-2-r-sata-6g-2.5-emlc.html
I want to use the 2 OCZ SSDs as mirrored intent log devices, but as the
intent log needs quite a small amount of the disks (10GB?), I was
wondering if I can use the rest of the disks as L2ARC?
I have a few questions about this:
-Is 10GB enough for a log device?
A log device, essentially, only needs to hold a single
transaction's-worth of small sync writes,
Actually it needs to hold 3 transaction groups worth.
There are 3 phases to ZFS's transaction group model: open, quiescing and
syncing.
Nowadays the sync phase is targetted at 5s so the log device needs to be able to
hold up to 15s of synchronous data.
so unless you write more than
that, you'll be fine. In fact, DDRdrive's X1 is only 4GB and works just
fine.
Agreed, 10GB should be fine for your system.
Neil.
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
