Fedora 11 To Default To the Ext4 File System

ffs writes "The next release of Fedora, 11, will default to the ext4 file system unless serious regressions are seen, as reported by heise online. The LWN story has a few comments extolling the virtues of the file system. Some benchmarks have shown ext4 to be much faster than the current default ext3. Some of the new features that matter for desktop users are a faster file system check, extents support (for efficiently storing large files and reducing fragmentation), multiblock allocation (faster writes), delayed block allocation, journal checksumming (saving against power / hardware failures), and others. The KernelNewbies page has more information on each feature. As is the extfs tradition, mounting a current ext3 filesystem as ext4 will work seamlessly; however, most new features will not be available with the same on-disk format, meaning a fresh format with ext4 or converting the disk layout to ext4 will offer the best experience."

How does it compare to ext2?

[Chemisor]

So where can I see some benchmarks showing just how much of a slowdown I can expect after switching from ext2 to ext4? All the benchmarks I see around here compare it to ext3 and to ReiserFS only. Also, is it possible to run ext4 without the journal? Any benchmarks on that? (Oh, and please, don't bother with the reliability lectures. I couldn't care less.)

Ext4 small files performance?

[Dogun]

I still haven't seen sensible benchmarks for ext4 with respect to how large directories scale, interleaved small file read and create, and small-file write with one fsync() at the very end (the only real world case.)

At this point, I have to wonder if the emporer has no clothes, or if the people posting benchmarks are just idiots.

Re:Ext4 small files performance?

[Anonymous Coward]

For those who are not filesystem wizzes, could you expand or provide a link on why this is important? I'm wanting to improve the performance of my boxes like everyone else but understanding the ins and outs of the filesystems is a weak point of mine. Thanks.

Re:Fresh format vs conversion

[radarsat1]

Good to know. Personally I'll be happy to use ext4 on new disks or when I'm really doing a complete re-install, but I'm in no hurry to "upgrade", seeing as my current ext3 disks are working just fine. I played with different filesystems once until I got some corruption and realized that one of the advantages of ext3 is that it's been around long enough that there are lots of tools to help with recovery and checking. So I'll probably stick with what I know until I have an opportunity to try out ext4, but I'm not going to go and reformat my disks right away.

Thank you Red Hat

[eparis]

I'm glad to see Red Hat and Fedora taking the hard steps to push our technology forward. Precious few organizations employ people to work on things like this, instead expecting others to do the hard work to create and integrate disruptive core technologys. I know Red Hat employs people to work full time on ext4 and they have a person working full time on btrfs (which by all early accounts is supposed to be revolutionary and kick the crap out of everything else out there [even the fabled ZFS] (it pains me to say thanks to oracle for btrfs, but one of their employees is the primary driver) Someone has to do the hard work of being a leader, putting in engineering time, and fixing the bugs before the fanboys can consume (and all too often get credit for) new technology. Thank you Fedora for both the freedom and the constant drive to be on the leading edge of technology.

Re:A few answers

[camperdave]

As is the extfs tradition, mounting a current ext3 filesystem as ext4 will work seamlessly;

Shouldn't that be the other way around? If you mount an ext4 filesystem as ext3 the system will work, using only the ext3 subset of ext4. However, if you mount an ext3 as ext4 the system will try to use ext4 data structures which are simply not on the disk.

... or am I missing something?

Re:Ext4 small files performance?

[jonaskoelker]

I suppose somebody cares about how well they can expect their 124GB file to stream to disk

I know for certain that I care about big-file performance in almost only these ways:

Can I write the file faster than the network sends it to me?

Can I read the file faster than the application (typically mplayer) needs to consume it?

When I know I shouldn't sit and wait for a larger task to continue, I really don't care how long it takes as long as I can do interactive stuff with good performance and the disk won't still be rattling when I go to sleep. Five minutes? An hour?

I'd rather have effort put into usability of disk management tools: four-way on-line resizing (left/right end moving left/right), on-line repacking (defragmentation) and on-disk format conversion, on-line repartitioning [which goes beyond the scope of ext4, of course] and things like that. A versioning file system would be cool, and btrfs snapshots sound like they'd be nice as well .

But that's the desires for my usage pattern, and I acknowledge that there are others.

Re:Ext4 small files performance?

[blueg3]

What he really means is having a new benchmark that has a combination of loads from other benchmarks -- this is closer to a real-world case than any one individual benchmark, which is some kind of extreme case.

Ext4 in Ubuntu jaunty jackalope

[the_one(2)]

Apparently there is a serious risk of data loss at this time in case of power loss (at least in ubuntu). http://ubuntuforums.org/showthread.php?t=1040199 [ubuntuforums.org]

FS choices in the Datacenter

[unixluv]

One of my biggest beefs with ext3 in the data center is the required fsck periodically. Redhat won't support jfs or xfs (which I can get from CentOs) but some vendors won't support anything that isn't on their supported platform list (IBM Clearcase for one).

So is ext4 going to force a fsck at boot, which takes 1/2 a day with ext3 on some of my multi-Tb systems? Will Redhat finally adopt a better server filesystem? These are the questions that some of us doing professional Redhat support are asking.

Re:Thank you Red Hat

[TheLink]

I wonder if many "edible discoveries" involved drunk young men daring each other to eat something.

Stuff like: century eggs, tofu, lutefisk, casu marzu (not sure if the last is really that edible ;) ).

Re:No

[Ivlis]

Linux is not communism. Part of the appeal of Linux is that Microsoft abuses its monopoly to eliminate competition (OS/2, BeOS, Wordperfect, QuickTime, etc...). By defending competition, freedom of choice and a free market, Linux defends capitalistic ideals. And people are allowed to sell Linux: SuSE does just that.