"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?
I don't have any idea up front. One thing comes to mind and that is
does your Quantum come up with "tagged queuing enabled". My IBM has
i have the same hdd, ibm dcas-34330W.
it is very interesting that "tagged queuing" was enabled for scsi driver
while i was working with freebsd-3.0-release
and became disabled (or isn't recognised) when i upgrade to
that disabled or more precisely never enabled, which makes it slower
and safer. My dmesg shows the drive as