Hey all -
Am just starting to look into the whole Sun Ops Centre thing, and it
seems quite nifty for doing LDOM provisioning etc.
My first attempt was using a Storage Library that lives on an NFS server
to provide the LDOM virtual-disk files.
I checked my baseline speed from my LDOM control/IO domain to the NFS
server, and 40-50MB/s (over gigabit) is pretty much standard. The disks
backing it SATA, and that's about as fast as I'd expect.
My understanding is that it breaks down something like
Big file created on NFS share by SunOpCentre
-> IO Domain mounts NFS share over IP
-> IO domain sees 'data' file, and uses that as the
backing store for the vdsdev
-> LDOM runs, and creates a zpool ontop of that.
And it's wayyy slow. About 4MB/s for sequential writes... (That's
opposed to the 40 - 50 MB/s for the sequential from the IO domain)
Also of interest is that when copying from the IO domain direct to the
NFS share, I can drive up to 500IOPS on the disks in the pool. I don't
usually get much more than 150 IOPS when I'm doing it from the guest ldom.
Soooo - Before I start getting all medieval on this - I guess I should
ask: Is this what I should expect? Should I expect blowful performance
because *every* write operation will be treated as synchronous by NFS
because of the way the filebased backend does it's disk accesses, and
it's pushing a bunch of synchronisation primitives to ensure consistency
on disk? (Or something like that?!?)
Has anyone seen *good* performance with this style of configuration?
Any thoughts to where I might get quick wins? (and no - I can't afford
SSD based ZIL devices... ;)
Cheers!
Nathan.
