Hello,
I have a Dell PowerEdge 2500 server with FC6 + latest updates installed.
For backup, I want to use 2 external disk drives, 300 GB each (all
internal stuff is SCSI). I bought a USB 2.0/FireWire combo card and am
running a few tests and to my great surprise, USB 2 (480 mbps) is way
faster than FireWire 400 (400 mbps). I get this from hdparm:
Connected as USB 2.0 drive:
hdparm -t -T /dev/sdd
/dev/sdd:
Timing cached reads: 948 MB in 2.00 seconds = 473.56 MB/sec
Timing buffered disk reads: 76 MB in 3.03 seconds = 25.11 MB/sec
Connected as FireWire 400 drive:
hdparm -t -T /dev/sdd
/dev/sdd:
Timing cached reads: 948 MB in 2.00 seconds = 473.05 MB/sec
Timing buffered disk reads: 32 MB in 3.07 seconds = 10.44 MB/sec
To make sure that hdparm is not messing with me, as the only reference I
find in its man page is relating to IDE and SCSI drives, I tested some
simple copy command of a 4 GB file. I did each command twice in a row,
to avoind any skewing of the results by anything in OS buffers.
USB 2.0 Mode:
time cp -v /home/db/pm/pm_10.d2 /media/extd/xxx3
`/home/db/pm/pm_10.d2' -> `/media/extd/xxx3'
real 3m20.819s
user 0m0.988s
sys 0m54.483s
[root@mars ~]# time cp -v /home/db/pm/pm_10.d2 /media/extd/xxx4
`/home/db/pm/pm_10.d2' -> `/media/extd/xxx4'
real 3m18.799s
user 0m1.048s
sys 0m54.791s
FireWire Mode:
time cp -v /home/db/pm/pm_10.d2 /media/extd/xxx1
`/home/db/pm/pm_10.d2' -> `/media/extd/xxx1'
real 7m33.109s
user 0m1.196s
sys 0m52.439s
[root@mars ~]# time cp -v /home/db/pm/pm_10.d2 /media/extd/xxx2
`/home/db/pm/pm_10.d2' -> `/media/extd/xxx2'
real 9m13.851s
user 0m1.108s
sys 0m55.191s
I used the same drive, a Maxtor 320 GB drive that was on sale recently,
which is mounted inside an Adaptec external USB/FireWire combo case.
Any ideas why FireWire is so much slower than USB? Should I look at the
card, the drive or the drivers? I would really like to use the FireWire
side of things, but not at this ridiculous speed.
Thanks for any pointers.
Chris
