Curt Wohlgemuth wrote: > On Mon, Jul 20, 2009 at 8:41 PM, Eric Sandeen<sandeen@xxxxxxxxxx> wrote: >> Xiang Wang wrote: >>> For comparison, I did the same experiment on an ext2 partition, >>> resulting in each file having only 1 extent. >> Interestinng, not sure I would have expected that. > > Same with us; we're looking into more variables to understand it. To be more clear, I would not have expected ext2 to deal well with it either, is more what I meant ;) I'm not terribly surprised that ext4 gets fragmented. For the numbers posted, how big were the files (how many 1m chunks were written?) Just FWIW; I did something like: # for I in `seq 1 16`; do dd if=/dev/zero of=testfile$I bs=1M count=16 oflag=direct & done on a rhel5.4 beta kernel and got: ~5 extents per file on ext4 (per filefrag output) between 41 and 234 extents on ext2. ~6 extents per file on ext3. ~16 extents per file on xfs if I created a subdir for each file: # for I in `seq 1 16`; do mkdir dir$I; dd if=/dev/zero of=dir$I/testfile$I bs=1M count=16 oflag=direct & done ~5 extents per file on ext4 1 or 2 extents per file on ext2 1 or 2 extents per file on ext3 ~16 extents per file on xfs. -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
