On Mon, 2005-10-03 at 14:16 -0700, Josh Berkus wrote: > Jeff, > > > > Nope, LOTS of testing, at OSDL, GreenPlum and Sun. For comparison, A > > > Big-Name Proprietary Database doesn't get much more than that either. > > > > I find this claim very suspicious. I get single-threaded reads in > > excess of 1GB/sec with XFS and > 250MB/sec with ext3. > > Database reads? Or raw FS reads? It's not the same thing.
Just reading files off the filesystem. These are input rates I get with a specialized sort implementation. 1GB/sec is not even especially wonderful, I can get that on two controllers with 24-disk stripe set. I guess database reads are different, but I remain unconvinced that they are *fundamentally* different. After all, a tab-delimited file (my sort workload) is a kind of database. > Also, we're talking *write speed* here, not read speed. Ok, I did not realize. Still you should see 250-300MB/sec single-threaded sequential output on ext3, assuming the storage can provide that rate. > I also find *your* claim suspicious, since there's no way XFS is 300% faster > than ext3 for the *general* case. On a single disk you wouldn't notice, but XFS scales much better when you throw disks at it. I get a 50MB/sec boost from the 24th disk, whereas ext3 stops scaling after 16 disks. For writes both XFS and ext3 top out around 8 disks, but in this case XFS tops out at 500MB/sec while ext3 can't break 350MB/sec. I'm hopeful that in the future the work being done at ClusterFS will make ext3 on-par with XFS. -jwb ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
