HEADS UP: SUJ Going in to head today
Jeff Roberson
jroberson at jroberson.net
Tue Apr 27 05:59:33 UTC 2010
On Sun, 25 Apr 2010, Scott Long wrote:
> On Apr 24, 2010, at 8:57 PM, Jeff Roberson wrote:
>> On Sun, 25 Apr 2010, Alex Keda wrote:
>>
>>> try in single user mode:
>>>
>>> tunefs -j enable /
>>> tunefs: Insuffient free space for the journal
>>> tunefs: soft updates journaling can not be enabled
>>>
>>> tunefs -j enable /dev/ad0s2a
>>> tunefs: Insuffient free space for the journal
>>> tunefs: soft updates journaling can not be enabled
>>> tunefs: /dev/ad0s2a: failed to write superblock
>>
>> There is a bug that prevents enabling journaling on a mounted filesystem. So for now you can't enable it on /. I see that you have a large / volume but in general I would also suggest people not enable suj on / anyway as it's typically not very large. I only run it on my /usr and /home filesystems.
>>
>> I will send a mail out when I figure out why tunefs can't enable suj on / while it is mounted read-only.
>>
>
> This would preclude enabling journaling on / on an existing system, but I would think that you could enable it on / on a system that is being installed, since (at least in theory) the target / filesystem won't be the actual root of the system, and therefore can be unmounted at will.
That's definitely true. Some users have had mixed success enabling it on
/. It looks like it is a bug either in g_access or ffs's use of g_access
which does not allow tunefs to write after a downgrade. I'm not yet sure
how this is presently working for the softdep flag itself, or if it
actually is at all.
To clarify my earlier statements: Journaling only makes sense when the
fsck time is longer than a few tens of seconds. So volumes less than a
gig or two don't really need journaling. It just costs extra writes and
fsck time will likely be similar. In some pathological cases it can even
be faster to fsck a small volume than it is to run the journal recovery on
it.
Thanks,
Jeff
>
> Scott
>
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