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Re: Possible funny with /sbin/fsck


On Mon, Jan 22, 2001 at 09:47:51AM +0000, Martin Hamilton wrote:
> Appears to be working so far, with a 300MB journal (based on the rule 
> of thumb in the ext3 README)

Actually, the rule of thumb reads

  Now, create a journal file.  I don't know how big it should be yet: the
  rules of thumb have yet to be established!  However, try (say) 2MB for a
  small filesystem on a 486; maybe up to 30MB on a big 18G 10krpm Cheetah.

Note the "up to".  30MB is meant to be an upper limit on a sane
journal size.  The optimal journal size depends on the filesystem's
write load, NOT on the size of the disk, so a 300MB journal is way too
large, and will end up pinning loads of stuff into memory!

> to check the non-root filesystems, we actually got a crash from the
> fsck parent process until we changed to serialized fscking, viz.

What sort of "crash"?  It sounds as if you ended up doing several
hundred MB of simultaneous journal replay because of the huge journal
sizes, and the system got bogged down into seeking all over the place.
That is going to be _really_ slow, but it should eventually complete.  

Ted, one thing I can't recall here offhand --- will e2fsck buffer all
the IO channel writes until flush, or will it write as it goes?  If
it's buffering things, then e2fsck journal replay could end up using a
lot of swap, and that's maybe something we want to fix.


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