Delete a directory, crash the system

[Kirk McKusick]

> Date: Mon, 06 Apr 2015 11:09:43 +1000
> From: Da Rock <freebsd-fs at herveybayaustralia.com.au>
> To: Kirk McKusick <mckusick at mckusick.com>
> CC: Benjamin Kaduk <kaduk at MIT.EDU>, freebsd-fs at freebsd.org
> Subject: Re: Delete a directory, crash the system
> 
> On 30/03/2015 05:46, Kirk McKusick wrote:
> 
>> Short of adding metadata redundancy to FFS, there is no solution. I
>> have actively avoided putting such features into FFS as FreeBSD already
>> has ZFS that does that (and many other things). My goal is to have a
>> highly performant filesystem with minimal resource requirements. It by
>> definition has limits, and administrator intervention in the face of
>> media errors is one of them.
>>
>> 	Kirk McKusick
> 
> I think I'm getting it, but I'm considering a different angle. With
> just SU if the computer goes off for whatever reason it insists on
> single-user mode (unless this has changed since); with SU+J it runs
> a quick check and boots normally. Hence better for less literate users.
> 
> I think I will stick with SU+J and fix as necessary though. Thanks
> for the help too Kirk.
> 
> Cheers

Both SU and SU+J reqiure single-user mode while they recover. The
key difference is that SU+J typically requires it for under a second
while SU can require it for minutes to hours depending on how long
it takes to run fsck (e.g., how big the filesystems are). So, to the
end user, SU+J is much less impactful since it appears as just a blip
as the compter reboots, while the delay of running fsck can seem
intermitable. Hence the default of running with SU+J.

	Kirk McKusick