[Python-Dev] Ext4 data loss

[Hrvoje Niksic]

Joachim König wrote:
> To me, the flaw seem to be in the close() call (of the operating 
> system). I'd expect the data to be
> in a persistent state once the close() returns.

I wouldn't, because that would mean that every cp -r would effectively 
do an fsync() for each individual file it copies, which would bog down 
in the case of copying many small files.  Operating systems aggressively 
buffer file systems for good reason: performance of the common case.

> Why has this ext4 problem not come up for other filesystems?

It has come up for XFS many many times, for example 
https://launchpad.net/ubuntu/+bug/37435

ext3 was resillient to the problem because of its default allocation 
policy; now that ext4 has implemented the same optimization XFS had 
before, it shares the problems.