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To: Da Rock <freebsd-fs@herveybayaustralia.com.au>
Subject: Re: Delete a directory, crash the system 
In-reply-to: <55169D02.8090107@herveybayaustralia.com.au> 
Date: Sat, 28 Mar 2015 15:02:20 -0700
From: Kirk McKusick <mckusick@mckusick.com>
Cc: freebsd-fs@freebsd.org
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> Date: Sat, 28 Mar 2015 22:22:26 +1000
> From: Da Rock <freebsd-fs@herveybayaustralia.com.au>
> To: Kirk McKusick <mckusick@mckusick.com>, Benjamin Kaduk <kaduk@MIT.EDU>
> CC: freebsd-fs@freebsd.org
> Subject: Re: Delete a directory, crash the system
> X-ASK-Info: Message Queued (2015/03/28 05:22:36)
> X-ASK-Info: Confirmed by User (2015/03/28 14:35:33)
> 
> On 26/03/2015 03:12, Kirk McKusick wrote:
> 
>> The suggestion to disable journalling is a good one. Journalling fixes
>> only consistency errors that it knows about and cannot handle media errors.
>> The sorts of panics you are getting are usually caused by media errors.
>> So disabling journally and checking all metadata after crashes (which is
>> what fsck does) should minimize your problems.
> 
> So my only option for journal is gjournal (slow) or zfs (memory hog) to 
> maintain consistency; is that it? Incidentally, why keep SU+J on as 
> default then? Wouldn't this be considered a bug still, then?

SU without journaling will maintain consistency. It is just that you
will need to run fsck after a crash. That is the way FFS has been since
it was written in 1982 and will allow you to recover from media errors
which it appears your system is suffering from. SU+J is just a faster
way of restarting but only works when you do not have media errors.

	Kirk McKusick