Vivek Khera writes:
what raid card have you got?
2 3ware cards.
I believe both are 9550SX
i'm playing with an external enclosure
which has an areca sata raid in it and connects to the host via fibre
channel.
What is the OS? FreeBSD?
One of the reasons I stick with 3ware is that it is well supported in
FreeBSD and has a pretty decent management program
it is wicked fast, and supports a RAID6 which seems to be
as fast as the RAID10 in my initial testing on this unit.
My next "large" machine I am also leaning towards RAID6. The space different
is just too big to ignore.
3ware recommends RAID6 for 5+ drives.
What drives are you booting from?
Booting from the 8 drive raid.
If you're booting from the 4-drive
RAID10, perhaps split that into a pair of RAID1's and boot from one
and use the other as the pg log disk.
Maybe for the next machine.
however, I must say that with my 16 disk array, peeling the log off
the main volume actually slowed it down a bit. I think that the raid
card is just so fast at doing the RAID6 computations and having the
striping is a big gain over the dedicated RAID1 for the log.
Could be.
Seems like RAID6 is supposed to be a good balance between performance and
available space.
Right now I'm testing an 8-disk RAID6 configuration on the same
device; it seems slower than the 16-disk RAID6, but I haven't yet
tried 8-disk RAID10 with dedicated log yet.
Is all this within the same controller?
i'd bump checkpoint_segements up to 256 given the amount of disk
you've got dedicated to it. be sure to increase checkpoint timeout too.
Thanks. Will try that.
