Le 8 févr. 09 à 13:44, David Magda a écrit :
On Feb 8, 2009, at 16:12, Vincent Fox wrote:
Do you think having log on a 15K RPM drive with the main pool
composed of 10K RPM drives will show worthwhile improvements? Or am
I chasing a few percentage points?
Another important question is whether it would be sufficient to
purchase only one 15K disk, or should two be purchased and they be
mirrored?
Worth repeating here...
it can be done but not necessary.
What would happen if the device that the ZIL lives on
suddenly goes away or start returning checksum errors?
nothing, the ZIL is just read in case of host failure/reboot.
Mirroring log devices helps to survive double failure scenario : (1
log device + host failure).
If log devices goes away the system starts to behave as if no separate
log was configured
and the zil just uses the main storage pool.
While an SSD is theoretically less likely to fail in some respects (no
mechanical parts), what happens if it fails?
synchronous writes starts to be handled at higher latency, nothing else.
How important is mirroring on log devices?
Another question comes to mind: if you have multiple pools, can they
all share one log device? For example, if you have twelve disks in a
JBOD, and assign disks 1-4 are in mypool0, disks 4-8 are in mypool1,
and disks 9-12 are in mypool2. Can you then have one SSD that can be
allocated as the log device for all the pools?
I'd think so, you just need to partition it 3-way.
-r
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
