amd64/177633: FreeBSD 9.1 and ZFS deadlocked at shutdown/reboot

Scott Kitchin scott at
Thu Apr 4 14:30:00 UTC 2013

>Number:         177633
>Category:       amd64
>Synopsis:       FreeBSD 9.1 and ZFS deadlocked at shutdown/reboot
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-amd64
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Apr 04 14:30:00 UTC 2013
>Originator:     Scott Kitchin
>Release:        9.1-RELENG r248699
FreeBSD web 9.1-RELEASE-p1 FreeBSD 9.1-RELEASE-p1 #0 r248699: Mon Mar 25 18:31:53 MSK 2013     root@:/usr/obj/usr/src/sys/NOVYSOFT  amd64

I tried FreeBSD 9.1 (RELEASE/RELENG/STABLE) with ZFS mirrored (raid1) pool and iRedMail ( and it hangs when I issue a shutdown command. The only last message displayed "All buffers synched" and it hangs indefinitely until I hit the reset/power button.

FreeBSD 9.1 with ZFS (raid1) pool shutdown hang/deadlock.
FreeBSD 9.1 without ZFS shutdown successful.
FreeBSD 9.0 with ZFS shutdown successful.
FreeBSD 9.0 without ZFS shutdown successful.

This only happens after I install iRedMail. If I uninstall or delete iRedMail and it shutdowns normal. If I reinstall iRedMail and it hangs. iRedMail's mail daemons must be causing some kind of deadlock and preventing FreeBSD 9.1 from normal shutdown. I think this is serious problem if the server is at a remote location without physical access to power button.

I was able to reproduce this problem in VirtualBox with two virtual drives for ZFS pool mirroring and two different computers.

The server can be shutdown using this command 'shutdown -n -o -r now' but it's risky.
1) Install FreeBSD 9.1 with ZFS mirrored (raid1) pools
2) Install Bash from ports
3) Install iRedMail from
4) Shutdown to start all services
5) Shutdown again and it hangs

I use ZFS creation tool from


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