So I'm doing an rsync between a ZFS filesystem on local SATA disks and
an empty ZFS filesystem on a drive connected via USB 2.0. zpool iostat
is showing me a write bandwidth of about 30M. That does mean 30MB/sec,
right? That's compatible with how long the test took.
I used up 47368826 blocks, du -s says here, or about 24GB. It took just
under 14 minutes, so 28MB/s rounded to whole numbers.
USB 2 is nominally 480 Mbits/s, which is 60Mbytes/sec, and one doesn't
expect to achieve nominal performance from disks connected via USB. So
if I'm getting 28MB/sec, half nominal, is that about the best I can
expect? Or is that poor? Disks themselves can do, what, 50MB/sec to
80MB/sec (this is definitely not a 10k or 15k rpm drive here)? The disk
in this box is an old PATA; would I be likely to notice the difference
with a modern SATA in a modern USB case?
How much better would Firewire 400 be? How much does it depend on the
controller? My M2n-sli-deluxe motherboard has IEEE 1394, and there are
some hits on 1394 in syslog during startup, so that looks vaguely
hopeful.
I'm not unhappy with backing up 24GB in 14 minutes, all in all.
--
David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info
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