Arun Tomar wrote:
hi!
guys.
i was trying to achieve the speeds mentioned according to the usb 2.0 specs.
http://en.wikipedia.org/wiki/USB_2.0#USB_2.0
Hi Arun,
What is the speed that you are expecting?
Line speed for USB Hi speed is 480 Mbits/s.
So it is 60 MB/s.
(Note the differences ib M*Bits* and M*Bytes*)
You are getting :
~18 MB/s on Read
~4 MB/s on Write
So, you are getting about 30% line rate (on Read).
I am not sure of what the software overhead exactly is, but it is
significant. Check out the rates that you can achieve in Windows. I am
not aware of something similar to dd on windows. Please keep
filesystems away from this exercise since it becomes hard to do apple to
apple comparison in such a case. I'll try and see if anyone is aware of
the numbers supposed to be.
i'm not anywhere near it. has anyone else faced similar issues.
use case:
i've a 16 gig usb 2.0 pen drive and an amd athlon dual core system with
usb 2.0 ports.
pasting my finding below
a...@opensolaris:/media# rmformat
Looking for devices...
1. Logical Node: /dev/rdsk/c11t0d0p0
Physical Node: /p...@0,0/pci1043,8...@13,5/stor...@6/d...@0,0
Connected Device: Kingston DT 101 II1.00
Device Type: Removable
Bus: USB
Size: 15.3 GB
Label: repo0906
Access permissions: Medium is not write protected.
Sep 11 20:03:07 opensolaris usba: [ID 912658 kern.info
http://kern.info] USB 2.0 device (usb951,1625) operating at hi speed
(USB 2.x) on USB 2.0 root hub: stor...@6, scsa2usb1 at bus address 3
Sep 11 20:03:07 opensolaris usba: [ID 349649 kern.info
http://kern.info] Kingston DT 101 II 001372982955F961061909AB
Sep 11 20:03:07 opensolaris genunix: [ID 936769 kern.info
http://kern.info] scsa2usb1 is /p...@0,0/pci1043,8...@13,5/stor...@6
Sep 11 20:03:07 opensolaris genunix: [ID 408114 kern.info
http://kern.info] /p...@0,0/pci1043,8...@13,5/stor...@6 (scsa2usb1) online
Sep 11 20:03:07 opensolaris scsi: [ID 583861 kern.info
http://kern.info] sd2 at scsa2usb1: target 0 lun 0
Sep 11 20:03:07 opensolaris genunix: [ID 936769 kern.info
http://kern.info] sd2 is /p...@0,0/pci1043,8...@13,5/stor...@6/d...@0,0
Sep 11 20:03:07 opensolaris scsi: [ID 107833 kern.warning] WARNING:
/p...@0,0/pci1043,8...@13,5/stor...@6/d...@0,0 (sd2):
Sep 11 20:03:07 opensolaris sd_get_write_cache_enabled: Mode Sense
returned invalid block descriptor length
This failure, it looks like, is disabling your write cache. You can
expect significant speed reductions because of this, which is what you
exactly see in your numbers.
Pavan
Sep 11 20:03:07 opensolaris genunix: [ID 408114 kern.info
http://kern.info] /p...@0,0/pci1043,8...@13,5/stor...@6/d...@0,0 (sd2)
online
Sep 11 20:03:07 opensolaris genunix: [ID 314293 kern.info
http://kern.info] device pciclass,030...@5(display#0) keeps up device
s...@0,0(disk#2), but the latter is not power managed
Sep 11 20:03:07 opensolaris pcplusmp: [ID 805372 kern.info
http://kern.info] pcplusmp: ide (ata) instance 3 irq 0xf vector 0x45
ioapic 0x2 intin 0xf is bound to cpu 1
a...@opensolaris:/etc/webmin# dd if=/dev/dsk/c11t0d0p0 of=/dev/null bs=32k
^C10042+0 records in
10041+0 records out
329023488 bytes (329 MB) copied, 18.0087 s, 18.3 MB/s
a...@opensolaris:~/Azureus Downloads/Fedora-11-i386-DVD# dd
if=Fedora-11-i386-DVD.iso of=/dev/rdsk/c11t0d0p0 bs=32k
112421+1 records in
112421+1 records out
3683829760 bytes (3.7 GB) copied, 865.186 s, 4.3 MB/s
--
Regards,
Arun Tomar
blog: http://linuxguy.in
website: http://www.solutionenterprises.co.in
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