At 17:00 31-8-2001 +0800, you wrote:
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 ...
It's just a matter of time.
> 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.
Your write speeds will be lower but not more then a single disk if the card
you are using is beefy enough. Raid5 involves a lot more overhead during
writes, we once noted a windows NT sytem going faster when one of the
harddisks in the raid5 failed. After that we converted it to raid10.
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
This is the redhat default as well as specified in /etc/rc.d/init.d/nfs
> 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
Note: The amount of buffers are shared between the nfsd processes, this
will results in 8KB buffer per deamon. If you run 16 deamons this will mean
you get 4KB per process.
Change acordingly.
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?
This is noted from the NFS HowTo but they do not state what adverse results
and under what version of the linux kernel. 2.4.9 might have this fixed but
I just don't know. I have not run into funny behaviour yet and I am
thinking of changing this option on the internet server gateway as well
since that one has 3 networkcards and simultaneous activity on all.
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.
That is what they say yes, I am just taking that risk. I have not
experienced anomelies in the other sytems yet. I can imagine that if you
are routing or packetfiltering this might lead to problems.
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? ;>
Nope, to deep for me. Never changed any of those defaults.
Cheers
--
Seth
Every program has two purposes one for which
it was written and another for which it wasn't
I use the last kind.
|