Hello, ext3. Goodbye, reiser4.

So I’ve been trying out various filesystems over the past few months, by converting a few machines to them and using them on a daily basis.

I’ve found that reiser3, JFS, and XFS are all risky and actually corrupt data on crashes. JFS also has a few weird bugs that make the kernel oops, and sometimes cause filesystem corruption. All of the above also have starvation issues, where one IO-intensive process can dramatically slow down everything on the system (by a factor of 100 or more).

Reiser4 has proven better — only one small issue that I can recall. But it’s got a huge problem: no ability to resize a Reiser4 partition. That is rather ridiculous these days, and really reduces the utility of LVM. (Hans says he’ll make it resizable when someone pays.)

So I’ve tried out ext3 again, for the first time in a few years. I’m using data=ordered,commit=300 (or 600 on some machines), which still makes it safer than the other journaled filesystems.

And I must say that it is impressive. The old bottlenecks that I was used to were gone. The thing is reliable and fast, and scales well. I’m going to move everything back to ext3.

So why do Hans’s benchmarks show reiser4 being better? For one thing, most benchmarks measure throughput, not response time, so things like starvation don’t cause black marks in them. Most of them don’t even use multiple processes to simulate real-world activity anyway. Plus, ext3’s default mount options (commit=5, for instance) are much more conservatve than other filesystem’s. To get a fair test, one should increase that commit= number on ext3.

Here’s another discussion about ext3.

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