i386/84589: 5.4-STABLE unresponsive during background fsck 2TB partition

[David Kirchner]

The following reply was made to PR kern/84589; it has been noted by GNATS.

From: David Kirchner <dpk at dpk.net>
To: bug-followup at freebsd.org
Cc:  
Subject: Re: i386/84589: 5.4-STABLE unresponsive during background fsck 2TB partition
Date: Fri, 30 Dec 2005 10:07:28 -0800

 This bug has been reproduced on a different server (similar hardware)
 running 6.0-RELEASE and UFS2. I accidentally forgot to disable
 background fscks on the server (big d'oh!) and about 12 hours after
 the server rebooted access to the disk started slowing down,
 eventually becoming completely unresponsive, forcing a reboot. The
 reboot took about 2 minutes to take effect, probably because the
 server was "busy" with the fsck.
 
 I was able to log in to it before it locked up, and tried ktrace'ing
 the fsck_ffs process. It had no activity. I suspect it deadlocked
 against something else.
 
 Unfortunately the server was a NFS server, so the NFS client also had
 to be rebooted due to a separate NFS client deadlock bug.
 
 The how-to-repeat is the same: That ^C fsck step is just to trigger a
 dirty filesystem. Really, really easy to duplicate.
 
 The workaround is the same: Disable background_fsck for all 5.4 or 6.0
 servers (or for any servers capable of performing a background fsck).
 
 FWIW: The foreground fsck takes far less than 12 hours to complete.