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Re: Playing around with NFS+XFS
On Thu, 30 Aug 2001 at 22:37, Seth Mos wrote:
> I use 16384 for 100Mbit at work which seems to be a decent size vs
> reponse ratio.
I'm too lazy to do yet more tests, so I'm taking your (Seth's) word for
it. << changing /etc/fstab >> ;>
> I have a few standard bonnie results of linux -> linux tests on my
> homepage http://iserv.nl/
I just checked it out and it's _significantly_ better than my results, and
my setup is supposed to pack more punch than yours in all aspects except
tuning (where I'm slowly learning thanks to you).
Hmm ...
> Server was a pIII 450 with 256MB of ram and a 2c905B NIC and a 40GB
> IDE disk in UDMA33 mode.
Mine is a Pentium III 733MHz with 512MB RAM, a TLAN 10/100MBps NIC running
100Mbps full-duplex, and 4 x 36GB UDMA/66 hard drives in hardware RAID5.
This is starting to get a little off-topic in that it's not XFS-specific
anymore. I hope everyone else will pardon it:
> I used 8 nfsd processes
Just a note, Debian's nfs-kernel-server package has this as the default
via the following in /etc/init.d/nfs-kernel-server:
RPCNFSDCOUNT=8
> and enlarged the buffer size from 64KB to 256KB.
> echo 262144 > /proc/sys/net/core/rmem_default
> echo 262144 > /proc/sys/net/core/rmem_max
I read somewhere that this can lead to some not-so-nice situations when
left like this instead of the default. Would you be able to qualify this?
I do remember reading somewhere that the recommended action will be to set
buffer sizes to 256KB, then start the NFS server, then revert to 64KB. I
was wondering if you'd have any information on that.
Now for something that I _think_ is a little more on-topic (but still not
quite XFS specific):
I tweaked my /proc/sys/vm/bdflush a little, bringing down age_buffer to
100 jiffies (1 second) from 3000 jiffies (30 seconds). I did this in the
hopes that idle systems would flush dirty buffers sooner. I left
everything at their defaults, which are:
nfract = 30
ndirty = 64
nrefill = 64
nref_dirt = 256
age_super = 60
o Did my bringing down age_buffer to 1 second make things too synchronous
that writes were significantly affected?
o Will bringing up nfract allow the system to perform better? Or will
this simply chunk up disk writes and make the system less responsive
during those buffer flushes?
o How will increasing or decreasing ndirty affect disk-intensive
operations like database updates or massive file transfers?
Hopefully those (like Seth Mos, hehehe) with much more administrative
experience than I can help out and recommend tuning parameters? I thank
Seth for the NFS tuning tips. Maybe if he has some hidden bdflush (or even
buffermem) secrets, he can share them with the list? ;>
Thanks a lot in advance!
--> Jijo
--
Federico Sevilla III :: jijo@leathercollection.ph
Network Administrator :: The Leather Collection, Inc.
GnuPG Key: <http://jijo.leathercollection.ph/jijo.gpg>