Slightly OT: Web server q's - SCSI vs. IDE

[Nik Clayton]

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On Tue, Oct 30, 2001 at 01:37:44PM -0000, Mark Hughes wrote:
> Hi guys. I know this is somewhat off-topic, but I know you're a
> knowledgable bunch of guys and hope you'll be able to give me some valuab=
le
> opinions on this subject.
>=20
> I'm still looking into our new server, and was wondering what peoples
> opinions were on SCSI vs. IDE vs. bucket loads of RAM for a database-heavy
> web site running under FreeBSD....

Bucketloads of RAM :-)

> >From what I've heard in the past, the bottleneck with databases (we use
> MySQL) is almost always the hard drive, so to that end, in terms of
> performance, how much difference will having SCSI drives make over IDE?

Depends how frequently you're hitting the disk, what the access patterns
are like, and how you've layed out the filesystem.  RAID of some sort
also makes a difference, as does the disks ability to do tagged queuing.

> Also, would having shedloads of RAM (looking at 1GB initially, because of
> the stupid prices at the moment) make any difference to the IDE vs SCSI
> equation? The entire of our database currently is only 100MB odd, is there
> any way to make MySQL cache *all* that data into RAM?

FreeBSD will cache it on demand.

> Likewise, would a vinum software RAID-0 or RAID-1 of two IDE drives make
> them better than a single SCSI drive? How would two SCSI drives in a RAID
> fair?

It really does depend on your access policy.  You make finger-in-the-air
estimates (as I'm doing now), but you really need to benchmark to get
the numbers and work out where the bottlenecks are.  vmstat, systat,
iostat, and others are all useful in gathering the sort of data you
need.

<plug>
Should you need a consultant to come in and set this sort of thing up
for you, give me a shout.  My rates are reasonable, and this is
bread-and-butter stuff for me.
</plug>

N
--=20
FreeBSD: The Power to Serve             http://www.freebsd.org/
FreeBSD Documentation Project           http://www.freebsd.org/docproj/

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