Operating System - OpenVMS
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Poor NFS Client Performance (again...)

Valued Contributor

Poor NFS Client Performance (again...)

OK, time to resurrect the faiings of the OpenVMS NFS client again.

Currently we use OpenVMS 7-3-2, some patches (Update V5.0), TCPIP v5-4 ECO5 running on DS10s and DS15s. I've had reports that when these machines run agains a unix NFS server the tansfer rate for files drops to below 0.3Mbytes per second (on a quiet netowrk, both sides reporting 100M full duplex). Turning off the generation of ADF files improves matters somewhat, transfer speeds go to about 0.8Mbytes per second, sometimes exceeding 1Mbyte per second.

The OpenVMS V2 client performs slightly better against the OpenVMS NFS server, generally around twice as fast although obviously a pair of DS15s does do a bit better.

I've tried the latest and greatest NFS client (v3) on a DS10 running OpenVMS 8-4 and can get transfer rates of around 3Mbytes a second against the unix system. A unix v3 NFS client looks to achieve 8Mbytes a second.

So, is there anyway to improve the performance of the V2 NFS client?

FWIW the mount command looks like this:

$ TCPIP mount dnfs2:
/server=unix/noadf -
/acp=(workset=20000) -
/noconvert -

AS far as I can tell the /ACP, /NOCOMVERT and /TRANSPORT switches make little or no difference. The v2 client on the OpenVMS 8-4 system is just as bad as that on the OpenVMS 7-3-2 system. The unix box is effectively a closed unit.

I'm kind of tied to using NFS at the moment, and seeing as there is not CIFS/SMB client for OpenVMS I can't event table a move to CIFs as a possibile solution.


Brian Reiter
Honored Contributor

Re: Poor NFS Client Performance (again...)


Check all potential bottlenecks! I remember dealing with a case where the speed was just fast enough to prove that it wasn't a 10MB ethernet segment, but way below theoretical network speed. After checking all possible network related entites, it finally dawned that it was a slow disk!

I don't suppose the source or destination are IDE disks?
A crucible of informative mistakes
Valued Contributor

Re: Poor NFS Client Performance (again...)

Hi John

Its SCSI disks all round. I'm going to set up a RAM disk and see if I can pass the blame onto the hard disk (I doubit it somehow).

For what its worth, FTP access to the same system is fine.