NFS performance question / (a)sync

NFS performance question / (a)sync

[Thorsten Göllner]

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Hi,

i just installed an current kernel (2.4.27) with NFS V3 support and want to access via an nfs-mount from another machine.

My /etc/exports look like that:
/data     clientname(rw,sync,no_root_squash)

I mount it with "mount -t nfs servername:/data /data". Nothing uncommon so far.

When copying a file to the NFS-server I get a speed of 0,5 - 2,0 megabyte per second. Not really much.

When changing my /etc/exports to (ASYNC):
/data     clientname(rw,async,no_root_squash)

I get a speed of about 11 megabyte per sonds. That is what I expect from a 100 Mbit-Ethernet-card.

Is it "normal" that I reach only 0,5 - 2,0 megabyte per socond when using sync-transfer? I know what this means, but I did not expect such a performance drop.

Because I want to setup a heartbeat-cluster (with drbd) I think I have to use SYNC. I will try ASYNC tomorrow, but I expect corrupted files when the primary server fails and the ressources switch to the secondary server (with nfs service takeover).

Thank for any comments,
-Thorsten-

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Re: NFS performance question / (a)sync

[Bernd Schubert]

Hi Thorsten,

> Is it "normal" that I reach only 0,5 - 2,0 megabyte per socond when using
> sync-transfer? I know what this means, but I did not expect such a
> performance drop.

did you get those results on the drbd device? This was just (this week)=20
discussed on the drbd list, see the archives. Sync vs. async was also just=
=20
discussed on this list.


Cheers,
 Bernd

=2D-=20
Bernd Schubert
Physikalisch Chemisches Institut / Theoretische Chemie
Universit=E4t Heidelberg
INF 229
69120 Heidelberg
e-mail: bernd.schubert@pci.uni-heidelberg.de


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