Blair Barnett wrote:
I have a simple shell script that writes numbers to a file and every 10
numbers does a sync and after 40 does a reboot. I've attached the script
to this email.
If the file is written to an EXT3 filesystem, then file contains the
numbers 1-40. However, if the file is written to an XFS 1.1,1.2, or 1.3
filesystem, then file contains the numbers 1-10.
Can someone tell me if this is a feature of XFS or a bug?
your in danger do get flamed ;-) though:
The man-page of mount states in the options for ext3:
data=journal / data=ordered / data=writeback
Specifies the journalling mode for file data.
Metadata is always journaled.
All data is committed into the journal prior
to being written into the main file system.
This is the default mode. All data is
forced directly out to the main file system
prior to its metadata being committed to the
Data ordering is not preserved - data may be
written into the main file system after its
metadata has been committed to the journal.
This is rumoured to be the highest-through
put option. It guarantees internal file
system integrity, however it can allow old
data to appear in files after a crash and
So, your ext3 does a data=ordered (if you didn't change it, obviously
you didn't, you would have known the man-page ;-) ), while xfs's
behaviour is more like data=writeback. In special circumstances this can
even lead to data loss on xfs (see a thread in linux-xfs@xxxxxxxxxxx,
metadata is written, extents for the file are zeroed out but data's not
written to, well should almost never happen in actual CVS kernel ;-)).
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