[clug] EXT4 Reliability

Daniel Pittman daniel at rimspace.net
Sat Oct 3 22:11:19 MDT 2009

Owen <rcook at pcug.org.au> writes:
> On Wed, 30 Sep 2009 21:56:16 +1000
> Paul Wayper <paulway at mabula.net> wrote:
>> On 29/09/09 21:58, Ben Nizette wrote:
>> > On Tue, 2009-09-29 at 20:38 +1000, Francis Whittle wrote:
>> >
>> >> That said, I'll tend to go for ext2 for backup media, for portability.
> The EXT4 Reliability thread was interesting. I wondered why reiserfs didn't
> get a mention.

Because it is an unmaintained[1], poorly designed[2], slow[3], and generally
unreliable[4] file system, at a guess.

If you still have data stored on a ReiserFS partition, move it somewhere else
before it is too late.

...and, yes, ReiserFS had some technical features, like tail packing, that are
not found in other filesystems.  Trust me, the cost of using something else is
not nearly as high as the cost of rebuilding after it screws you...

> Now having been educated on the evils of ext4, I wasn't going to be caught,
> no sir! So decided to install Fedora-11 on a ext3 files system.

Well, I wouldn't trust ext4 with my backups, and I wouldn't use it for any
machine that I couldn't risk the data on, but it is written by cautious and
sensible people.

You probably don't risk very much using it as, say, the root partition on a
laptop or something — and it *is* much faster than ext3.

> Inserted the Cd and duly clicked on all the right buttons. When I hit the
> *GO* button, a dialog box appeared which said, words to the effect, "Hey
> fella, you can't do that, the fs has to be ext4 to match the CD".

Heh.  Fun times.


[1]  No upstream, Chris Mason at SuSE, who had the last commercial interest in
     it, has moved on to BTRFS.

[2]  fsck tools are a disaster; it can't differentiate between the filesystem
     metadata and an image of a filesystem stored on it, so never put an
     uncompressed ReiserFS image inside a ReiserFS partition.[5]

[3]  The efforts to reduce "big kernel lock" use inside ReiserFS have beet
     abandoned, so it is pretty much the most contention-prone filessytem in
     the kernel.  Plus, the BKL is slow, and crazy, and SMP is now standard,
     so it is also costly.

[4]  http://lmgtfy.com/?q=reiserfs+corruption

[5]  ...and yet they provided a library version of ReiserFS and encouraged
     application developers to adopt it as a composite file format to store
     unrelated parts — which would lead to significant numbers of embedded
     images inside a ReiserFS system...

✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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