Folks-
We have a switched 100Mb Ethernet network and run a variety
of UNIX workstations including a newer Sun clone workstation
(Solaris 2.6) and several new DEC Personal Workstations 500au
(4.0D patch#2). The Sun machine is a fileserver and has a
Dec RAID box attached to it. The Dec PWs are fileservice
clients. For us datafile sizes range from about 15Mbyte to
60Mbyte. The Dec PWs NFS-mount disks that are located in the
Sun/RAID box.
Since installing the Dec workstations, we have been trying to
find out the optimum placement of data disks to maximize data
throughput. If it is faster to have a 9Gbyte data disk on one of
the Dec PWs then we might do that. In the course of testing
possible options, we have observed the following strange results
for pushing NFS data across our network:
Copying a 15 Mbyte file either to/from a local disk from/to the
NFS mounted disk.
Server Client NFS Read Write
version
alpha alpha v2 2.6 11.3
alpha alpha v3 2.6 5.0
sun4u alpha v2 2.4 13.7
sun4u alpha v3 16.0 3.3 !!!!!!
alpha sun4u v2 2.7 13.6
alpha sun4u v3 2.6 4.7
Notes:
The read column gives the time to go from NFS to local (NFS read time),
the write column gives the time to go from the local to the NFS (NFS
write time). All of the above timings were repeated several times, and
each time the NFS filesystem was unmounted and remounted between any
runs to ensure no NFS caching.
It makes no real difference:
if the mount is hard or soft
if the protocol is udp or tcp
if you try to change the read/write buffer size
if you change the number of nfsd daemons running on the server
If you avoid NFS and just check net speed using INET socket write
and reads, the sun4u machine has no problem maintaining
100 Mbits/sec to/from an alpha (socket results in about 10 Mbytes/sec).
We would like to understand why we get slow write times over
NFS and if there is anything we can do about it. Our users have to
write 60Mbyte files frequently and I would like to speed up that
part of the data analysis process.
We particularly want to understand why a Sun machine reads an
NFS version 3 mounted partition (exported from a Dec PW machine) so
slowly.
Thanks.
mike
lizrdegg_at_ntrnet.net
Received on Wed Feb 17 1999 - 16:05:56 NZDT