Optimising NFS for system files
bernard at dugas-family.org
Wed Dec 31 07:52:10 UTC 2008
Wojciech Puchar wrote:
>> nfsserver# time tar -cf - clientusr-amd64 > /dev/null
>> 5.001u 12.147s 1:23.92 20.4% 69+1369k 163345+0io 0pf+0w
>> client9# time tar -cf - /usr > /dev/null
>> tar: Removing leading '/' from member names
>> 3.985u 19.779s 4:32.47 8.7% 74+1457k 0+0io 0pf+0w
>> Note : clientusr-amd64 is around 1.3GB and is the same directory
>> exported to client9 /usr with nfs.
> it's FAST. what's wrong?
First thing that may be wrong is the understanding of the time figures.
The documentation is not clear about them and the -h option is not working :
client6# time -h tar -cf - /usr > /dev/null
-h: Command not found.
0.000u 0.000s 0:00.00 0.0% 0+0k 0+0io 0pf+0w
The main thing is that the 3rd figures 1:23.92 and 4:32.47 seems to be
the time i wait in front of the computer while it works (ok, i know, i
should enjoy a beer, or hot coffee with this nice snow ;-) :
client9# date ; time tar -cf - /usr > /dev/null ; date ;
Wed Dec 31 08:23:59 CET 2008
tar: Removing leading '/' from member names
4.103u 19.651s 4:25.80 8.9% 74+1453k 0+0io 2pf+0w
Wed Dec 31 08:28:25 CET 2008
and 08:28:25 - 08:23:59 = 00:04:26 is very close to 4:25.80.
On server, it means : 1440MB / 84s = 17MB/s
On client, that becomes : 1440MB / 266s = 5.4MB/s
I know the disk is not very fast, but i would like the NFS layer not to
add too much...
I don't want my users to wait between 3 or 4 times more because computer
is using NFS.
I have plenty of cpu and bandwidth available : something is slowing the
process that should not... But what ? How to diagnose NFS ? Where should
i look in a logical diagnosis process ?
Bernard DUGAS Mobile +33 615 333 770
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