Thanks for the answers and suggestions.
I tried booting with the last KNOPPIX (3.7) live CD using 2.4.27 kernel and did some benchmarks:
- copying files from /dev/hda2 to /dev/hdd10 = 16 MB/s
- copying files from /dev/hdd10 to /dev/hda2 = 26 MB/s
Reminder: /dev/hda is a Seagate Barracuda 120GB/7200rpm/8MB cache ST3120026A) /dev/hdd is a Seagate Barracuda 80GB/5400rpm/2MB cache (ST380021A) /dev/hda2 is ext2 and /dev/hdd10 is FAT32
As you suggested Jeff, it seems clear from the above benchmarks that the writing speed of the target disk can be a bottleneck.
Also tried booting KNOPPIX with the 2.6.9 kernel:
- copying files from /dev/hda2 to /dev/hdd10 = 14 MB/s
- copying files from /dev/hdd10 to /dev/hda2 = 20 MB/s
Apparently the 2.6.9 kernel is slightly slower! (I was not expecting that.)
As for my very SLOW file transfer problem under FC3 (2.4 MB/s) I just realized that I was booting with ide=nodma :-(
I had to use this option when I booted from my FC3 CD1 otherwise the mediacheck would fail. I can't remember then if the FC3 installer put that ide=nodma boot option in my grub.conf file for me or if I had the very bad idea to do it myself. The fact is I have been booting my system with this nasty option since the first day I've installed FC3. And it remained here even after several kernel updates (I'm currently with the 2.6.9-1.681_FC3 kernel). I can't blame the kernel packagers for that: they are doing a nice job by replicating the kernel parameters introduced by the user (even nuts ones) to the new entry in grub.conf. This is all my fault!
So after removing the ide=nodma everything works FINE. Benchs are now:
- copying files from /dev/hda2 to /dev/hdd10 = 19 MB/s
- copying files from /dev/hdd10 to /dev/hda2 = 23 MB/s
It's interesting to compare the FC3 vs KNOPPIX benchs (both with DMA enabled):
- FC3/2.6.9 vs KNOPPIX/2.6.9: FC3 is faster
- FC3/2.6.9 vs KNOPPIX/2.4.27: FC3 is faster for the hda2->hdd10 copy but slower for the hdd10->hda2 copy
Cheers,
Hervé
