Thor Kristoffersen wrote:
(It looks like my reply never made it to the list so I'm trying again.)
Eric Sandeen <sandeen@xxxxxxxxxxx> writes:
David Chinner wrote:
On Mon, Mar 31, 2008 at 08:26:00PM +0200, Thor Kristoffersen wrote:
I've noticed that when I spin down XFS-mounted disks they spin up again
shortly afterwards. I used iostat to monitor disk accesses to a mounted
partition (with noatime) in single user mode. Apparently there is a write
access to the partition approximately every 35 seconds, even if the
partition is idle. As far as I can understand, since there is no data that
needs to be flushed this must be done by an XFS daemon for some purpose.
Use blktrace, or echo 1 > /proc/sys/vm/block_dump to see what block and
who's writing it... it's probably the superblock? what kernel?
This is kernel version 2.6.24. More specifically it's a Debian kernel from
package linux-image-2.6.24-1-686 (2.6.24-4).
I put the system in runlevel 1 and executed the test as you suggested. On
/dev/sda3 I have mounted (with noatime) an XFS filesystem that contains
data that is not supposed to be accessed by any process. In the output
below I have filtered out all accesses to other partitions. (BTW, this is
not actually the disk that I wanted to spin down, but I think the log
proves my point.)
I'm wondering if that is writing to the xfs ondisk log/journal in those cases.
What does 'xfs_logprint -t' show in these "idle" states
after these writes?
--Tim
Thor
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