ext4 and data consistency
Posted May 15, 2010 9:57 UTC (Sat) by anton
In reply to: ext4 and data consistency
Parent article: The Next3 filesystem
No filesystem goes out and corrupts the dpkg database,
but dpkg failing to properly ensure on-disk consistency might make it
possible for an untimely power failure (or whatever) to trash its
The file system does not have to go out to do it, because it was
entrusted with that data; so it can just fail to keep it consistent
while staying at home. A good file system will properly ensure
on-disk consistency without extra help from applications (beyond
applications keeping the files consistent from the view of other
How often do you pull the plug while dpkg is running?
Never. And I doubt it happens in a significant number of cases for
Ubuntu users, either. And the subset of cases where ext3 corrupts the
database is even smaller. That's why I questioned the drag's claim.
That's why robustness is so hard -- it's almost impossible to test.
And that's why I find the attitude that not the file system, but
applications should be responsible for data consistency in case of an
OS crash or power outage absurd. Instead of testing one or a few file
systems, thousands of applications would have to be tested.
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