I don't have any personal experience with backuppc, but I'll still chime
in with what I know:
>
> 1. Should I keep the 72 GB drive for OS, or put it on the RAID?
>
I would. Booting from a RAID array can be tricky. Not impossible, but I
personally don't think it's worth the effort. It sounds like you have an
old server box anyway, so you shouldn't be lacking space of connections
for a third drive.
>
> 2. I can add another CPU (P III 550 MHz) processor to the box - is it
> worth the effort to find one? I found one source for $5/CPU, I just
> need to find the heat sink and mounting hardware. Will this improve
> performance?
>
Of course it will, but on a simple backup machine, it won't really
matter much. I have a Debian-based software RAID-5 setup running on a
1.2GHz VIA chip with 256MB RAM. Is it slow? Sure, but only when I'm
trying to encrypt something or rebuilding the array (4x500GB drives,
~1.5TB array, full rebuild on a replaced drive takes about 10 hours). It
does rsync, ftp, smb and scp/ssh just fine..... even at the same time.
Sure your 500MHz chip is probably slower, but probably not by much. If
you want to play, go for it, but I wouldn't consider it a requirement.
>
> 3. The box has a built-in SCSI 68-pin Ultra2/wide bus/controller, but
> SCSI drives are more expensive, at least from a cursory google search.
> Is this correct? I don't think I can use SCSI drives within my budget
> constraint.
>
SCSI is faster, but if you're running SATA-II you'll have plenty of
speed. Your bottleneck is going to be the 100-baseT connection, which
even an ATA/33 drive could keep up with (see the bus speeds link below).
Unless you are running a production server and have a ton of constant
disk access (and you don't), SCSI won't really offer you much. Not worth
the cost for most consumer applications as far as I'm concerned.

Bus speeds:
http://en.wikipedia.org/wiki/List_of_device_bandwidths#Computer_buses_.28storage.29
>
> 4. Would upgrading the memory to 1GB improve performance - top shows:
> Mem: 646676k total,      639300k used     7376k free,      64548k buffers
> This would add another ~$60 to my cost.
>
Sure, why not. Again, I'm running 256MB and doing just fine though....
>
> 5. Should I look at hardware RAID cards - they seem very cheap, so
> perhaps software is better?
>
Cheap hardware RAID is fakeraid.... Google that one. The card does all
its work through the CPU so you don't really save anything. The only
thing that's useful is that it looks like 1 drive to the OS.... but if
that card ever fails and you can't get your hands on another one, you
could be SOL. Softraid, on the other hand, should port properly from
install to install, even from distro to distro. I've never had any
problems with mine. I would highly recommend just getting a SATA-II card
and staying away from fakeraid personally. I run the Promise TX4 card (4
SATA-II ports on a normal PCI interface, $60 shipped on newegg) and it
works flawlessly with Debian and Ubuntu.
>
> 4. Does this plan make sense, or is there a better way to proceed for
> about the same cost?
>
Sounds solid enough. You could probably find a NAS/USB/Firewire/eSATA
enclosure that would offer on-board mirroring, but that's going to be
kind of expensive, it may be difficult to replace drives and you won't
have the unfettered control you get from running a real machine. I've
read a lot of horror stories with the enclosures corrupting the entire
dataset too. You have the machine already, you just need the drives and
a controller card, I'd stick with that if I were you.

One thing to consider too is that 750GB and 1TB drives have come down in
price dramatically. If you're running a mirror (which I assume you are)
and you have the budget, you might consider springing for larger drives
from the start. That'll theoretically give you some more time before you
have to revisit the setup and upgrade the drives again.

Hope that helps.

-Joe
---------------------------------------------------
PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
To subscribe, unsubscribe, or to change your mail settings:
http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss