To those moving to Jaunty: Do not use the new ext4

Jonas Norlander jonorland at
Thu Mar 12 09:29:38 UTC 2009

2009/3/12 Dotan Cohen <dotancohen at>:
>> I haven't read all comments and I'm no expert on file systems but as
>> far as i know ext4 is a journaling file system and by that it should
>> guarantee that only complete writes of a file should be registered and
>> if thats not the case the old file should be intact and not truncated.
>> Apparently thats not the case with ext4 so what have I missed?
> No, writes are cached. Allegedly, KDE is depending on the cache and
> not syncing. This is bad when the write delay is measured in minutes
> (ext4) as opposed to seconds (ext3).

So we would see the same behavior with ext3 if the time between syncs
was the same?

I later read Theodore Ts'o (one of the developer) comment 45 an
explanation why and how:

But I still cant understand, no matter if you depending on the cache
or the libraries you using don't use flush() the right way isn't a
journaling file system supposed to only register complete transactions
and by that guarantee (of course you cant guarantee that, but it
should be minimal) that the files would not be destroyed/truncated?

/ Jonas

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