12 Oct
2004
12 Oct
'04
7:31 a.m.
On Tue, 12 Oct 2004, Jules Richardson wrote:
(I think you misread this -- without special preparation,
you'll never get > 25 - 50 Mbits/sec through it; that's 5
megabytes/sec peak.
But even this is a false measure; it's not realistic or
practical to size a system by the very tip of peak performance
requirements. More empirical tests are appropriate: how long does
it ACTUALLY take to explode mail? What portion of that is spent
on-disk? (My guess, from actually working with giant mailers, is
90% of the time is spent on the net tied up in TCP-open waits!)
Where's IDE these days relative to SCSI?
Very, very good. Except for really demanding jobs, which mail
and ftp archive is not, SCSI is a waste of money.
SCSI controllers
(RAID or otherwise) were always better than IDE - plus you get the
higher reliability, more flexible bus options etc.
Times change! Drives are far cheaper; >> reliability may still
exist in SCSI, but it's not been borne out in my experience.
If you've
got a 100Mbit ether, it's unlikely it will exceed
the disk or OS speed.
Not so convinced about that - remember that's bits, not bytes; ethernet
isn't *that* fast (relative to other things). As for mirroring to a seperate machine (if that's
what you were
intending) then disk performance should easily outstrip network
bandwidth
Even a fair EIDE system on a modern machine will keep 100megabit
ether 100% soaked 100% of the time if you're just copying
data over a wire. But rarely is that how files are moved,
and certainly not over the open internet!
(and could probably upset the underlying mail software
whilst
mirroring was taking place) -
I simply don't believe this. This is what OS's *do*. Or maybe
I misread this. Temp files disappear during backups all the
time, it's rarely a problem (occasional "file disappeared!" in
the log).
I'd go for a seperate ethernet link
between machines just for mirroring purposes in that case.
Utter waste of time. It could improve stopwatch times to complete
a mirror; but who cares unless the time is significant? This is
what computers *are for*, to do drudgery. If you've got the
ethernet on board, by all means, but otherwise it's a waste
without an actual need.
Unless you have a tightly-specified problem and constraints,
it's best to solve problems when the occur.