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: | Kenneth D. Merry (ke...@kdm.org) | |
| Date: | Jul 2, 2000 10:55:02 pm | |
| List: | org.freebsd.freebsd-stable | |
On Sun, Jul 02, 2000 at 20:42:53 -0400, David Gilbert wrote:
"Kent" == Kent Stewart <kste...@3-cities.com> writes:
I then noticed that the IDE would crashdump somewhere around 10 times faster than the SCSI disk.
Why? Can the SCSI speed be improved?
Kent> It depends on what 2940 and what IDE drive you are talking Kent> about. I have a Maxtor UDMA66 that is 20MB/s faster in some
I don't think this explains it at all. It would appear that the SCSI driver is running in some "extra safe" mode, or something. It has 512M to write sequentually to a partition... and the counting on the screen, we're looking at 2 to 3 seconds-per-megabyte (on a drive that delivers write performance of about 10M/s in normal operation).
Maybe what I should have said that the ratio of regular operation to dump performance of the ide driver is about 1:1 while it's 10:1 for the SCSI driver... why is this?
When the da(4) driver does a dump, it uses the CAM transport layer's polled completion/action facility, xpt_polled_action().
It looks like there is a substantial delay (1ms) in that routine between poll intervals.
If you'd like it to go faster, you'll most likely have to ask Justin about it. (i.e., I didn't write it.)
Ken
-- Kenneth Merry ke...@kdm.org
To Unsubscribe: send mail to majo...@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message