The maximum transfer rate in reading/writing ide disks connected via usb
2.0 seems to be 12MByte/sec. I would have expected 30-40MByte/sec. The
rate is more or less the same with a 2.5" 60G drive and a 3.5"
160G/7200rpm drive (using different enclosures, although both genesys
chips). Is there some magic I am missing? I get around the same rate
with ext3 and reiserfs (options notail,noatime). The 160G disk is
capable of 50+MByte/s transfer rates.
These values are much the same for my laptop (1.5G Pentium-m + Mandriva
2.6.12-12mdkcustom) and desktop (AMD64 2800 + gentoo 2.6.14-gentoo-r2,
also 2.6.13....)
/sys/block/sdb/device/max_sectors is normally 256 (seems to give around
the best results, but very little variation down to 64, see below for
typical figures.
echo 32 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 26 MB in 3.00 seconds = 8.67 MB/sec
[EMAIL PROTECTED] /]# echo 64 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 32 MB in 3.05 seconds = 10.49 MB/sec
[EMAIL PROTECTED] /]# echo 128 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 36 MB in 3.10 seconds = 11.61 MB/sec
[EMAIL PROTECTED] /]# echo 240 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 36 MB in 3.00 seconds = 12.00 MB/sec
[EMAIL PROTECTED] /]# echo 256 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 40 MB in 3.12 seconds = 12.82 MB/sec
[EMAIL PROTECTED] /]# echo 512 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 40 MB in 3.10 seconds = 12.90 MB/sec
[EMAIL PROTECTED] /]# echo 1024 >/sys/block/sdb/device/max_sectors
[EMAIL PROTECTED] /]# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads: 40 MB in 3.15 seconds = 12.70 MB/sec
hdparm output:
/dev/sdb:
readonly = 0 (off)
readahead = 256 (on)
geometry = 24321/255/63, sectors = 390721968, start = 0
lsusb:
Bus 007 Device 008: ID 05e3:0702 Genesys Logic, Inc. USB 2.0 IDE Adapter
Usbview outputs:
Host controller:
HCI Host Controller
Manufacturer: Linux 2.6.12-12mdkcustom ehci_hcd
Serial Number: 0000:03:00.2
Speed: 480Mb/s (high)
Number of Ports: 5
Bandwidth allocated: 0 / 800 (0%)
Total number of interrupt requests: 0
Total number of isochronous requests: 0
USB Version: 2.00
Device Class: 09(hub )
Device Subclass: 00
Device Protocol: 01
Maximum Default Endpoint Size: 8
Number of Configurations: 1
Config Number: 1
Number of Interfaces: 1
Attributes: e0
MaxPower Needed: 0mA
Interface Number: 0
Name: hub
Alternate Number: 0
Class: 09(hub )
Sub Class: 00
Protocol: 00
Number of Endpoints: 1
Endpoint Address: 81
Direction: in
Attribute: 3
Type: Int.
Max Packet Size: 2
Interval: 256ms
IDE drive:
USB TO IDE
Speed: 480Mb/s (high)
USB Version: 2.00
Device Class: 00(>ifc )
Device Subclass: 00
Device Protocol: 00
Maximum Default Endpoint Size: 64
Number of Configurations: 1
Vendor Id: 05e3
Product Id: 0702
Revision Number: 0.33
Config Number: 1
Number of Interfaces: 1
Attributes: c0
MaxPower Needed: 96mA
Interface Number: 0
Name: usb-storage
Alternate Number: 0
Class: 08(stor.)
Sub Class: 06
Protocol: 50
Number of Endpoints: 2
Endpoint Address: 81
Direction: in
Attribute: 2
Type: Bulk
Max Packet Size: 512
Interval: 0ms
Endpoint Address: 02
Direction: out
Attribute: 2
Type: Bulk
Max Packet Size: 512
Interval: 125us
Any suggestions? Thanks in advance
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