On Wed, Dec 02, 2009 at 03:57:47AM -0800, Brian McKerr wrote: > I previously had a linux NFS server that I had mounted 'ASYNC' and, as one > would expect, NFS performance was pretty good getting close to 900gb/s. Now > that I have moved to opensolaris, NFS performance is not very good, I'm > guessing mainly due to the 'SYNC' nature of NFS. I've seen various threads > and most point at 2 options; > > 1. Disable the ZIL > 2. Add independent log device/s
We have experienced the same performance penalty using NFS over ZFS. The issue is indeed caused by the synchronous nature of ZFS. More precisely, it is caused by the fact that ZFS promises correct behaviour while eg. a linux NFS server (using async) does not. The issue is decribed in great detail at http://blogs.sun.com/roch/entry/nfs_and_zfs_a_fine If you want the same behaviour as you had with your Linux NFS server, you can disable the ZIL. Doing so should give the same guarantees as the linux NFS service. The big issue with disabling the ZIL is that it is system-wide. Although it could be an acceptable tradeoff for one filesystem, it is not necesarily a good system-wide setting. That is why I think the option to disable the ZIL should be per-filesystem (Which I think should be possible because a ZIL is actually kept per-filesystem). As for adding HDD's as ZIL-devices, I'd advise against it. We have tried this and the performance decreased. Using SSD's as the ZIL is probably the way to go. A final option is to accept the situation as it is, arguing that you have traded performance for increased reliability. Regards, Auke -- Auke Folkerts University of Amsterdam
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