Thanks everyone for the suggestions. To summarize:
* There's no point in using SSD's for the operating system (except an
incredibly fast boot speed, and probably a bit lower system system
temperature / power usage - but because of the rest of the components in
the system it doesn't matter). I could probably use a USB key directly
connected to the USB type A connector on the motherboard.
* Using a separate disk for logging might give problems if the log
device goes wrong. To avoid this - keep the log on the disk pool, or
mirror the log device.
* A SSD drive as a log device would increase read speed over network
based sharing protocols (NFS or SMB, which will be used at the location
of this server)
* Disk performance increased by adding SSD cache and log devices will
die out (to a speed slower than the spindle disks) when the log and
cache disks once have been filled up to its maximum capacity. So the use
of SSD disks for cache and log is a waste of money and drive bays.
* Use DDR-based drives like DDRDrive (or i-RAM ?) for ZIL
I am still able to reorganize the use of the SSD disks (reinstall
OpenSolaris), and even replace any one of them with 2.5" spindle disks,
so any more suggestions are highly welcome.
I will do some more performance tests during my work day tomorrow.
Regards,
PeO
P-O Yliniemi skrev 2010-08-06 12:44:
Hello!
I have built a OpenSolaris / ZFS based storage system for one of our
customers. The configuration is about this:
Motherboard/CPU: SuperMicro X7SBE / Xeon (something, sorry - can't
remember and do not have my specification nearby)
RAM: 8GB ECC (X7SBE won't take more)
Drives for storage: 16*1.5TB Seagate ST31500341AS, connected to two
AOC-SAT2-MV8 controllers
Drives for operating system: 2*80GB Intel X25-M (mirror)
ZFS configuration: Two vdevs, raid-z of 7+1 disks per set, striped
together (gives a zpool with about 21TB storage space)
Disk performance: around 700-800MB/s, tested and timed with 'mkfile'
and 'time' (a 40GB file is created in just about a minute)
I have a spare X25-M drive of 40GB to use for cache or log (or both),
but since the disk array is a lot faster than the SSD-disk, I can not
see the advantage in using it as a cache device.
Is there any advantages for using a separate log or cache device in
this case ?
Regards,
PeO
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