On Fri, Jul 3, 2009 at 9:47 PM, James Lever<j...@jamver.id.au> wrote: > > On 04/07/2009, at 10:42 AM, Ross Walker wrote: > >> XFS on LVM or EVMS volumes can't do barrier writes due to the lack of >> barrier support in LVM and EVMS, so it doesn't do a hard cache sync like it >> would on a raw disk partition which makes the numbers higher, BUT with >> battery backed write cache the risk is negligible, but the numbers are >> higher then those on file systems that do do a hard cache sync. > > Do you have any references for this? and perhaps some published numbers > that you may have seen?
I ran some benchmarks back when verifying this, but didn't keep them unfortunately. You can google: XFS Barrier LVM OR EVMS and see the threads about this. >> Try XFS on a raw partition and NFS with sync writes enabled and see how it >> performs then. > > I cannot do this on the existing fileserver and do not have another system > with a BBWC card to test against. The BBWC on the LSI MegaRaid is certainly > the key factor here, I would expect. > > I can test this assumption on this new hardware next week when I do a number > of other tests and compare linux/XFS and perhaps remove LVM (though, I don't > see why you would remove LVM from the equation). When you do send me a copy, try both on a straight partition then on a LVM volume and always use NFS sync, but when exporting use the no_wdelay option if you don't already that eliminates slow downs with NFS sync on Linux. -Ross _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
