In the course of trying to track down some disk performance issues, I'm
trying to mount an XFS partition on a (slow) SCSI disk synchronously via
the fstab entry:
/dev/sda1 /mnt/test xfs logbufs=8,sync 0 0
However, I'm not getting the behavior I would expect:
[root@brian root]# time dd if=/dev/zero of=/mnt/test/bigfile bs=1024k
count=512; time umount /mnt/test
512+0 records in
512+0 records out
real 0m57.848s
user 0m0.000s
sys 0m3.280s
real 1m6.472s
user 0m0.000s
sys 0m0.610s
So the 'dd' returns after 1 minute, but it takes it another minute to
actually unmount the partition (during which there is lots of writing
going on). I tried adding 'osyncisdysnc', which ISTR is the default now,
and it (obviously) didn't help.
Am I misinterpreting what's going on here? Is this the expected behavoir?
The kernel is 2.4.18 from the 1.1 release.
Thanks.
--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University
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