On Tue, 31 Jul 2001, Sam Varshavchik wrote:
> Charlie Watts writes:
>
> > I have a dual-proc PIII 500MHz, 512MB Ram, single 10/100 NIC, plus a
> > couple of SCSI disks for system and logging and a couple of mirrored
> > UDMA66 IDE disks on dedicated controllers for mail storage.
>
> You should swap them around. You should use the SCSI disks for mail
> storage, and IDE disks for system and logging.
>
> SCSI will handle concurrent access much better than IDE, irrespective of the
> comparative bus speeds.
I agree, but was financially limited at the time they were bought. The
SCSI disks are tiny, ancient, and slow.
The IDE drives are brand new IBM DTLA disks, though. I've got tagged
queuing turned on - not sure if Linux does that yet, or if it's just a
FreeBSD + DTLA thing right now. It's a -really- big win on IDE disks - it
essentially lets you trust IDE write-caching, which I wouldn't trust
otherwise. And they are both on their own controllers, so despite being
mirrored concurrent access isn't a problem.
They do need more CPU baby-sitting than SCSI, even though they are UDMA -
I get enormous sequential I/O speeds, and very good random speeds ... but
at the cost of CPU loading. The load average on this box is -always- about
.3, though, so I'm not worried yet.
I have no pretentions that new IDE is equal to new SCSI, but I tested
it quite a bit before moving it into production - and these new IDE
disks with new IDE controllers work much better than old SCSI. Much better
seek times, and the mirroring helps the concurrency issue as well.
And despite not trusting IDE hardware particularly much, I'm comfortable
enough with them mirrored.
Despite all that - and being happy the way it is - SCSI is the way to go.
I'd always recommend it. But I couldn't afford it at the time.
--
Charlie Watts
[EMAIL PROTECTED]
Frontier Internet
http://www.frontier.net/
