(Sorry for cross-posting; I'm not on either ext3-users or linux-xfs, but I thought both lists might find this interesting. CC me with any replies or questions. Thanks.) (The last four paragraphs contain the interesting bits. Basically, XFS hath kick-ed the *ss of ext3 under conditions that are, for our company, critical.) Some listees might be interested in some testing I did the other day, XFS vs. ext3. In our last IMAX film project, right at crunch time, we were getting a whole bunch of dropped frames during compositing. Our compositing program would report "invalid file" partway through writing, and move on to the next frame. A year earlier we had done a very similar project, and stressed the system in very similar ways, but not seen the same problem at all. Difference? Last year we were using XFS, this year we were using ext3. Otherwise, as far as I could tell, the setups were identical. As far as I could tell; film projects differ in subtle ways, and that can have a big impact on how hard the filesystems are stressed. This Sunday I decided to test my hunch. We had to know for sure; if frames were also dropped with XFS under test, or if the test didn't show any dropped frames with either filesystem - in other words, if the problem was a Murphy's Law problem, refusing to show itself until the worst possible moment - we figured we'd be forced to spend a couple of hundred thousand dollars on servers and fabric for our next big IMAX project. The time needed to check for dropped frames and re-render frame-by-frame when a deadline is rushing up - to babysit - is simply too expensive. The test setup: 4 Shake compositing stations running on Win2k, communicating, via Samba, with a 1/2TB Linux server with an IDE software RAID5 setup, over GigE. Shake's job was simply to pump through 48MB Cineon frames from local drives to the server as fast as possible. I ran tests continuously for about 12 hours; I had to be able to guarantee my results. The results were clear and dramatic. Anywhere from 2 to 44 dropped frames out of 200 with ext3. (The worst ext3 numbers came while overwriting already existing files.) Zero dropped frames with XFS. Nadda. None. After the first few clear XFS tests I put extra load on the machine while the tests were running to see if that would make XFS hiccough - copying large files around internally, spawning CPU-eating programs. It didn't. Well... not until I threw a fork bomb at it, anyway. <smirk> But even then, it kept on chuggin' till the load average was somewhere over 900. Conclusion, clear as a bell: XFS for high-bandwidth data transfer over Samba... when running IDE software RAID5, anyway. Oh yeah - another interesting note: There were also dropped frames under ext*2*, which I tried just as a comparison case. XFS truly does, in the patois of the time, r0x0r... Andrew Klaassen _______________________________________________ Ext3-users@redhat.com https://listman.redhat.com/mailman/listinfo/ext3-users
