On Fri, 5 Oct 2007, Andrew Clayton wrote:
On Fri, 5 Oct 2007 06:25:20 -0400 (EDT), Justin Piszcz wrote:
So you have 3 SATA 1 disks:
Yeah, 3 of them in the array, there is a fourth standalone disk which
contains the root fs from which the system boots..
http://digital-domain.net/kernel/sw-raid5-issue/mdadm-D
Do you compile your own kernel or use the distribution's kernel?
Compile my own.
What does cat /proc/interrupts say? This is important to see if your
disk controller(s) are sharing IRQs with other devices.
$ cat /proc/interrupts
CPU0 CPU1
0: 132052 249369403 IO-APIC-edge timer
1: 202 52 IO-APIC-edge i8042
8: 0 1 IO-APIC-edge rtc
9: 0 0 IO-APIC-fasteoi acpi
14: 11483 172 IO-APIC-edge ide0
16: 18041195 4798850 IO-APIC-fasteoi sata_sil24
18: 86068930 27 IO-APIC-fasteoi eth0
19: 16127662 2138177 IO-APIC-fasteoi sata_sil, ohci_hcd:usb1, ohci_hcd:usb2
NMI: 0 0
LOC: 249368914 249368949
ERR: 0
sata_sil24 contains the raid array, sata_sil the root fs disk
Also note with only 3 disks in a RAID-5 you will not get stellar
performance, but regardless, it should not be 'hanging' as you have
mentioned. Just out of sheer curiosity have you tried the AS
scheduler? CFQ is supposed to be better for multi-user performance
but I would be highly interested if you used the AS scheduler-- would
that change the 'hanging' problem you are noticing? I would give it
a shot, also try the deadline and noop.
I did try them briefly. I'll have another go.
You probably want to keep the nr_requessts to 128, the
stripe_cache_size to 8mb. The stripe size of 256k is probably
optimal.
OK.
Did you also re-mount the XFS partition with the default mount
options (or just take the sunit and swidth)?
The /etc/fstab entry for the raid array is currently:
/dev/md0 /home xfs
noatime,logbufs=8 1 2
and mount says
/dev/md0 on /home type xfs (rw,noatime,logbufs=8)
and /proc/mounts
/dev/md0 /home xfs rw,noatime,logbufs=8,sunit=512,swidth=1024 0 0
So I guess mount or the kernel is setting the sunit and swidth values.
Justin.
Andrew
The mount options are from when the filesystem was made for sunit/swidth I
believe.
-N Causes the file system parameters to be printed out without
really creating the file system.
You should be able to run mkfs.xfs -N /dev/md0 to get that information.
/dev/md3 /r1 xfs noatime,nodiratime,logbufs=8,logbsize=262144 0 1
Try using the following options and the AS scheduler and let me know if
you still notice any 'hangs'
Justin.
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