[K12OSN] USB v2.0 HD throughput
mrjohnlucas at gmail.com
Mon Mar 5 11:01:55 UTC 2007
I recently bought a 500GB SimpleTech USB hard drive to back up my three home
Linux machines. After ridding the drive of the NTFS filesystem and replacing
it with an ext2 filesystem with "parted", I started backing up the data
folders on my new laptop (home directory, photos, music etc.). The throuhput
was dismally slow.
After some experimentation I discovered that the bottleneck was the KDE
"kio_slave" process (my normal desktop is KDE). Below are the results of three
quicky "benchmarks": copying the same 170MB ISO file from the system drive to
the USB drive. All runs were on the same computer to the same locations.
The results of this are interesting: KDE was by far the worst performer, Gnome
is much faster, but for pure performance, always go through the regular kernel
filesystem. The "kernel I/O" was acheived by mounting the drive the old
fashioned way, rather than relying on the desktop managers:
mount /dev/sdb1 /mnt/usb
KDE I/O throughput: 1.75Mbytes/sec.
Gnome I/O throughput: 17Mbytes/sec.
Kernel I/O throughput: 25Mbytes/sec.
Timings need to include flushing the I/O buffers, so "sync" times
are added to copy times for the calculations.
jlucas at toto ISO]$ time cp olpc-livecd.iso /media/disk/Toto ; time sync
[jlucas at toto ISO]$ time cp olpc-livecd.iso /media/disk/Toto ; time sync
[jlucas at toto ISO]$ time cp olpc-livecd.iso /mnt/usb/Toto ; time sync
"History doesn't repeat itself; at best it rhymes."
- Mark Twain
| John Lucas MrJohnLucas at gmail.com |
| St. Thomas, VI 00802 http://mrjohnlucas.googlepages.com/ |
| 18.3°N, 65°W AST (UTC-4) |
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