NFS - slow

[Rick Macklem]

Wojciech Puchar wrote:
> > the server is required to do that. (ie. Make sure the data is stored
> > on
> > stable storage, so it can't be lost if the server crashes/reboots.)
> > Expensive NFS servers can use non-volatile RAM to speed this up, but
> > a generic
> > FreeBSD box can't do that.
> >
> > Some clients (I believe ESXi is one of these) requests FILE_SYNC all
> > the
> > time, but all clients will do so sooner or later.
> >
> > If you are exporting ZFS volumes and don't mind violating the NFS
> > RFCs
> > and risking data loss, there is a ZFS option that helps. I don't use
> > ZFS, but I think the option is (sync=disabled) or something like
> > that.
> > (ZFS folks can help out, if you want that.) Even using
> > vfs.nfsrv.async=1
> > breaks the above.
> 
> 
> thank you for answering. i don't use or plan to use ZFS. and i am
> aware of
> this NFS "feature" but i don't understand - even with syncs disabled,
> why
> writes are not clustered. i always see 32kB writes in systat
> 
The old (default on NFSv3) server sets the maximum wsize to 32K. The
new (default on 9) sets it to MAXBSIZE, which is currently 64K, but
I would like to get that increased. (A quick test suggested that the
kernel works when MAXBSIZE is set to 128K, but I haven't done much
testing yet.)

> 
> when running unfsd from ports it doesn't have that problem and works
> FASTER than kernel nfs.
But you had taken out fsync() calls, which breaks the protocol, as above.

rick

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