Academic workstations -- Followups to comp.unix.questions ONLY

[Barry Shein]

>This should give you better performance because local 
>disks should be faster than networks, but it also adds to the cost and 
>administration effort.
>
>                                                Rick Daley
>                                                rpd at Apple.COM

Bad guess, go measure it, because servers almost always have faster
disks, controllers and bigger disk buffers remote disks are usually
faster than local disks (assuming a reasonable network loading which
doesn't have to be zero.)

An ethernet can deliver data at almost 1MB per second, go look at the
specs on your standard 27msec SCSI cheapo, 20KB/sec is not unusual for
maximum disk transfer rate, about 1/40th the speed of an ethernet.

In some cases remote disks are much faster, particularly where the
server CPU is much faster (and the disk system) and your process is
causing some amount of parallelism to occur (this doesn't have to be
purposeful, something simple like a find with a grep on each file can
end up exploiting both CPUs as one resolves the file system as the
other pumps away at the raw data.) Remember all those gripes about the
overhead of namei()? Where do you think namei() is running in an NFS
environment?

Many network load problems are due to badly configured or managed
networks with lots of junk traffic (eg. ARP or other broadcast
screamers going unchecked.)

However, I will agree that blaming it on the diskless workstations is
a wonderful alibi, the yokels believe you and rarely ask you to
actually do your job and find out what's really causing the problem.

It's the diskless workstations, it's the diskless workstations (we
know those diskless workstation users will never buy the local disks
you recommend so it's a safe bet to blame it on them.)

Another problem is political, the enforced memory shortage has
temporarily made the disk/memory balance unnatural. But don't confuse
economic realities with technical ones.

I agree none of this would apply to a Mac-II acting as an NFS server,
it doesn't support the disk architecture necessary to get any
performance advantage over a local disk.

I am not saying there aren't cases where a diskful workstation is far
better, I'm just saying most people don't know what they're talking
about or have motives other than understanding the technology.
-- 
	-Barry Shein

Software Tool & Die, Purveyors to the Trade
1330 Beacon Street, Brookline, MA 02146, (617) 739-0202