NFS databases

Bill Pearson wrp at dayhoff.med.Virginia.EDU
Thu Jun 22 21:27:49 EST 1995

In article <1995Jun21.162255 at ebi.ac.uk>, Roy Omond <Roy.Omond at ebi.ac.uk> wrote:
>In article <DAI3s3.8t6 at murdoch.acc.Virginia.EDU>,
>wrp at dayhoff.med.Virginia.EDU (Bill Pearson) writes:
>[...snip snip...]
>> gbmam.seq is about 23Mbytes, so on the alpha, the program was reading
>> and searching >1 Mb/sec, without any degredation by simultaneous
>> searches elsewhere.  fgrep on the same file took 33 sec, while cat
>> from the NFS system to the local system took 57 sec.
>Jeez... 23 Mbytes in 20 seconds real time translates into something
>like 1.15 Mbytes/second which equates to 9.2 Mbits/second (excluding
>packet overhead).
>Was this over a standard Ethernet ?  If so, then that's more than
>92% utilisation...

This was standard ethernet, but in re-testing the searches I learned
that the timings, while accurate, were not informative.  I did the
same search three times, and the real elapsed times were: 33, 18.4,
18.7, and 18.4 sec.  It seems clear that the Alpha/OSF/1 is buffering
the NFS mounted databases, so that the network was not being used for
the 18 sec runs.

But even at 33 sec for 23 Mbytes, a large fraction of the bandwidth
is being used. (I do these things at night.)

wrp at virginia.EDU
Dept. of Biochemistry #440
U. of Virginia
Charlottesville, VA 22908

More information about the Info-gcg mailing list

Send comments to us at biosci-help [At] net.bio.net