Re: Need to remove a ghost file, but can't because it doesn't exist
On Mon, Nov 20, 2006 at 09:52:26PM -0500, hendrik@topoi.pooq.com wrote:
> On Mon, Nov 20, 2006 at 06:43:06PM -0500, Johan Kullstam wrote:
> >
> > I have recently switched from reiserfs to jfs....
>
> > So far so good, but then again, I was largely happy with reiserfs over
> > the past 4 or so years. I must not tax my systems too hard with
> > panic reboots.
>
> >From what I hear, reiserfs and ext3 are both reasonably protected
> against panic reboots -- the hard drives will have written or not
> written the journal, and remounting the file system will figure out what
> happened. What they have a hard time with is panic powerdowns --
> because of the behaviour of some IDE drives -- apparently they report
> data transfer complete when they have merely buffered it internally,
> expecting it to be written real soon now. If the power fails before
> this happens, the file system will assume data have been written which
> in fact have not been written, and this could caouse journal failure.
>
> ext2, I'm told, has just enough extra redundancy that is is possible to
> make a reasonable guess as th owhat's wrong by an fsck. rumour has it
> that reiser, which stored data in a tree structure that's somewhat
> independent of the file-system structure, is more vulnerable to problens
> like confusing data with file-system structure.
>
> I don't know what the situatin is with JFS. Anybody know?
>
All I know is what I've experienced and what I have taken on faith:
Reiserfs looses files on panic powerdowns (power failure) even if the
filesystem structure survives. Reiserfsck doesn't fix this. This, for
me, has been small files (unfortunaly, typically those in /etc) even
though they weren't being written at the time of the power failure.
IBM says they designed JFS to allow a server to get back to work quickly
after a power failure, which includes fixing problems so that it __can__
work. I have enough experience with IBM to trust that when they design
something to put their name on it (and use it in AIX) that it will do
what they say it will do.
I tried to stress-test JFS by __moving__ directories from one drive to
another and one partition to another and cutting the power in the
middle. The move would only be partially complete but no files were
lost; they either existed on one drive or the other, nothing got lost in
limbo.
Until I got my new Athlon system, I have always used old/slow hardware.
Looking at the benchmark comparisions, reiserfs may be faster with small
files because it embeds them in the directory structure but to do that
it needs a lot more CPU overhead. So on my hardware, JFS has been
faster than reiserfs.
So I use JFS for everything.
Doug.
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