16 messages in org.freebsd.freebsd-stableRe: Dump takes ages on SCSI. (severa...| From | Sent On | Attachments |
|---|---|---|
| David Gilbert | Jul 2, 2000 1:24 pm | |
| Kent Stewart | Jul 2, 2000 2:53 pm | |
| David Gilbert | Jul 2, 2000 5:42 pm | |
| Kent Stewart | Jul 2, 2000 6:50 pm | |
| Chad R. Larson | Jul 2, 2000 8:44 pm | |
| David Gilbert | Jul 2, 2000 9:25 pm | |
| Kenneth D. Merry | Jul 2, 2000 10:55 pm | |
| David Malone | Jul 3, 2000 12:01 am | |
| kostik | Jul 3, 2000 1:35 am | |
| Gerhard Sittig | Jul 3, 2000 10:38 am | |
| Mike Smith | Jul 3, 2000 6:57 pm | |
| Mike Smith | Jul 4, 2000 4:08 am | |
| Mike Smith | Jul 4, 2000 5:22 am | |
| Gerhard Sittig | Jul 4, 2000 10:16 am | |
| Mike Smith | Jul 6, 2000 2:36 am | |
| Don Lewis | Jul 14, 2000 1:36 am |
| Subject: | Re: Dump takes ages on SCSI. (several times faster on IDE) | |
|---|---|---|
| From: | Kent Stewart (kste...@3-cities.com) | |
| Date: | Jul 2, 2000 2:53:24 pm | |
| List: | org.freebsd.freebsd-stable | |
David Gilbert wrote:
I have a PIII/450 with a venerable Adaptec 2940UW and a Quantum 9G SCSI disk.
Recenly, I was generating many crash dumps and was using a serial console (so I was watching them). I came to a point in my debugging where I needed another PCI slot, so I removed the 2940 and loaded an IDE drive with the same build of FreeBSD.
I then noticed that the IDE would crashdump somewhere around 10 times faster than the SCSI disk.
Why? Can the SCSI speed be improved?
It depends on what 2940 and what IDE drive you are talking about. I have a Maxtor UDMA66 that is 20MB/s faster in some situations than my 2940uw with an older IBM drive probably comparable to your Quantum. The IBM benchmark peaks at 8MB/s and has a smaller cache. The random performance of the IBM is many times the Maxtor (10x at least); however, on sequential read/writes the Maxtor really shines. I think that a dump would be comparable to my sequential write situation. It was explained to me that the scsi can schedule random read/writes and the IDE can't. A server needs random read/writes and uses the scsi to its benefit. One of these new lvd controllers and drives (80+MB/s min) would do wonders to your performance during the dump.
Kent
Dave.
-- ============================================================================ |David Gilbert, Velocet Communications. | Two things can only be | |Mail: dgil...@velocet.net | equal if and only if they | |http://www.velocet.net/~dgilbert | are precisely opposite. | =========================================================GLO================
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