Question Regarding e2fsck
tytso at mit.edu
Thu Jun 24 14:44:14 UTC 2004
On Thu, Jun 24, 2004 at 12:23:23AM -0500, Sam Williams wrote:
> I've run ext3 filesystems for the last few years and I've never seen
> this question answered..... If a system shutsdown hard, even with
> journaling is it at all necessary to run e2fsck?
It's best to just always run e2fsck. Yes, you can just simply mount
an ext3 filesystem after a crash, since the kernel has code to run the
journal; this is necessary if the root filesystem is a journalled ext3
filesystem. However, it's better to let userspace (i.e. fsck/e2fsck)
take care of things from that point, for the following reasons:
1) E2fsck will run the journal automatically, and if the filesystem is
otherwise clean, it skip doing a full filesystem check.
2) If the filesystem is not clean (because during the previous run the
kernel noticed some filesystem inconsistencies), e2fsck will
automatically do a full check if it is necessary.
3) If you have multiple disks, fsck will run multiple e2fsck processes
in parallel, thus speeding up your boot sequence than if you let the
kernel replay the journal for each filesystem when it tries to mount
it, since then the journal replays will be done sequentially, instead
of in parallel.
The bottom line is that the all of the default major distributions are
doing the right thing, and they are running e2fsck on ext3 filesystems
for a good reason.
So in answer to your question, no it is not ***necessary*** to run
e2fsck, however, it is a good idea, and it will not slow down your
boot time any to do so, and in fact if you have multiple hard drives,
it will likely speed things up.
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