[mythtv-users] diskless frontend nfs throughput

belcampo belcampo at zonnet.nl
Fri Aug 7 08:28:42 UTC 2009


Jim Stichnoth wrote:
> On Thu, Aug 6, 2009 at 11:05 AM, Dan Littlejohn<dan.littlejohn at gmail.com> wrote:
>> I have a gentoo diskless frontend that mounts using nfs and it seems like
>> the throughput of nfs is slow.  iperf show the network able to push 770 Mb/s
>> and hdparm shows the sata disk on the server at 90 Mb/s, but doing a dd
>> across the network only shows up as 10 Mb/s  (is about 40 Mb/s when the same
>> test is done on the server to a third machine).
>>
>> Odd thing is that the pxeboot mounts nfsver2.  Not sure if this is a problem
>> or not, but other mounts after boot mount as nfsver3.  Really seems like it
>> is a config problem with nfs somewhere, but I have not found anything that
>> makes a difference.  Doing rsize=8k,wsize=8k, noatime, async.  Anyone have
>> any tips to look for or is this 10 Mb/s really the throughput I should
>> expect for a diskless frontend?
Remove those rsize=8k,wsize=8k, the default of current kernels is 
rsize=1048576,wsize=1048576
Client/server negotiate max possible blocksize.
If server is defaulting to a 'not optimum' block-size you can override 
that with
echo 1048576 > /proc/fs/nfsd/max_block_size
in one of your initscripts
> 
> My diskless MythDora 10.21 frontend uses NFS.  I timed a copy of a 4GB
> file from the NFS server into /dev/null and got about 41 MB/s (or 330
> Mb/s).  This is over a gigabit wired network.  The only special mount
> option to speak of is "nolock" presumably because the lockd is not
> part of the initrd image.
> 
> Jim
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