Re: Appropriate dirve size for Oracle DB

From: Fred A G <nospam_at_allowed.localhost>
Date: Fri, 26 Jan 2001 00:26:43 +0100
Message-ID: <lD2c6.207$pq6.229@nntpserver.swip.net>

"edipko01" <edipko01_at_home.com> wrote in message news:3A70BDE1.9010906_at_home.com...
> I understand and agree with everything below, but still have a similar
> question.
>
> Say you need 36gig of space and only have one scsi channel(40Mbits/s),

If you have a ultra scsi channel in wide (16bit), it is actually ~40MB/s (20MHz x 16 bit). But that is a very theoretical figure. Perhaps you can get 30-35 real MB/s. I would like to see a benchmark now when there are disks, at least if you can trust manufacturers spec's, that can sustain
>40MB/s.

> using 4-9gig drives gives you what you need for capacity and max
> throughput (4-10Mbit/s drives = 40Mbits/sec).
>

More spindles is the way to go to "parallellize" I/O. Often, in a multi-user environment the I/O is small & random, why you should look at IOPS, not the "marketing" limits of the drive. With I/O request sizes at 8 or 16K you probably have more like 1-3 MB/s, not 10MB/s, so the bandwith of the scsi channel should be a less important problem (still don't put all your disk on one controller, if you can afford it). Drive latencies are always a pain, even with those 15krpm drives ;-)

> My question is, since the price difference between 9gig and 18gig
drives
> was only around $50ea., is there any performance (or other) problem
> using 4-18gig drives? Throughput remains the same up to 72gig now.
>

Make sure those drive really are in the same class/series before you buy.

Regards
/Fad Received on Thu Jan 25 2001 - 17:26:43 CST