Syncing disks, buffers remaining - value increases?

dpk dpk at
Mon Aug 1 18:38:44 GMT 2005

Sorry for all the questions to the list, we're having a number of issues
deploying FreeBSD 5.4 and we're trying to get an understanding of what
we're seeing.

When I reboot these servers (using "reboot" on the command line), it will
go through the usual routine I'm familiar with from FreeBSD 4.x, but when
it goes to the "syncing disks"  phase, sometimes it will do something like

Syncing disks, buffers remaining ... 1 1 1 1 1 2 1 1 1 3 1 1 1 1

Eventually it gives up on 1 or so buffers. When the server comes back up,
it gives warnings that the partitions were all improperly dismounted.

Is it normal for the number of buffers remaining to actually increase
while shutting down? I'm looking at the kernel source and the loop that
performs these syncs appears pretty small. Could something else still be
running on the server that is trying to write to disk, even while in the
shutdown phase? I guess it would only be able to run "interrupt threads",
judging by the comments, while it releases Giant.

It may be a coincidence, but on a few occasions, the background fsck may
have still been running when the reboot was issued. I've assumed that
since fsck now runs in the background that it must be able to gracefully
handle reboots.

FreeBSD 5.4-RELEASE-p5, Dual proc Xeons (varying speed), varying memory,
PAE+SMP kernels, 3ware RAID cards (varying capacity, RAID levels).

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