Hi,
Had some questions about automatic boot-time fsck, following a power-loss or
hard-shutdown, etc.
All prior research (web searching, etc) on this has been inconclusive.
1) Does it do a real fsck or only a journal playback?
2) If it's a real fsck, is it done in repair mode or diagnostic mode?
Also, do the answers depend/vary according to ext4 version or anything else?
Thank you
On 7/16/14, 9:55 PM, Daniel wrote:
> Hi,
>
> Had some questions about automatic boot-time fsck, following a power-loss or
> hard-shutdown, etc.
> All prior research (web searching, etc) on this has been inconclusive.
>
> 1) Does it do a real fsck or only a journal playback?
By default, e2fsck at boot time only replays the journal if
needed.
A full fsck at boot time is generally only done if:
*) The filesystem was marked with an error prior to the fsck due
to a runtime metadata error
*) Mount-count or time-based thresholds have been reached
(newer mke2fs doesn't set these threshold by default)
> 2) If it's a real fsck, is it done in repair mode or diagnostic mode?
Depends on how initscripts invoke it, but most likely
it is in preen ("repair the easy stuff") mode.
> Also, do the answers depend/vary according to ext4 version or anything else?
yep, see above, w.r.t. initscript behavior, older/newer mke2fs,
e2fsck.conf, mke2fs.conf, etc ;)
-Eric
> Thank you
>
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On Jul 16, 2014, at 9:14 PM, Eric Sandeen <[email protected]> wrote:
> On 7/16/14, 9:55 PM, Daniel wrote:
>> Hi,
>>
>> Had some questions about automatic boot-time fsck, following a power-loss or
>> hard-shutdown, etc.
>> All prior research (web searching, etc) on this has been inconclusive.
>>
>> 1) Does it do a real fsck or only a journal playback?
>
> By default, e2fsck at boot time only replays the journal if
> needed.
To elaborate a bit further - e2fsck will always do a sanity check of
the superblock when it is opening the filesystem to replay the journal.
> A full fsck at boot time is generally only done if:
>
> *) The filesystem was marked with an error prior to the fsck due
> to a runtime metadata error
or if the error was stored in the journal, even if it couldn't be
written to the superblock.
Cheers, Andreas
> *) Mount-count or time-based thresholds have been reached
> (newer mke2fs doesn't set these threshold by default)
>
>> 2) If it's a real fsck, is it done in repair mode or diagnostic mode?
>
> Depends on how initscripts invoke it, but most likely
> it is in preen ("repair the easy stuff") mode.
>
>> Also, do the answers depend/vary according to ext4 version or anything else?
>
> yep, see above, w.r.t. initscript behavior, older/newer mke2fs,
> e2fsck.conf, mke2fs.conf, etc ;)
>
> -Eric
>
>
>> Thank you
>>
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>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>> the body of a message to [email protected]
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
>
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> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
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Cheers, Andreas
Ok, got it.
Thank you both very much for your help - it's greatly appreciated.