Slow USB disk input output on the Sheevaplug

[mgiann]

Hello,

I have setup my sheevaplug with ubuntu and root on the USB disk. The Disk is an 1Tb Iomega device.

The mount points look like:
/dev/sda2 on / type ext3 (rw,noatime)
/dev/sda1 on /boot type ext2 (rw)
/dev/sda4 on /mnt/data type ext4 (rw,nosuid,noatime)

When copying a file on the plug (the ext4 filesystem) I get speeds of about 1Mb/s. Similar speeds occur when I copy files across  the network. However, when I connect the USB drive to a laptop, I get speeds of more than 10 Mb/s. And that is the average speed of a 60 Gb copy  where many files are transfered.

I don't know how to track this problem down. Can you please suggest a few causes for such a problem or diagnostics I to run?

Regards,

[mgiann]

Here are some more details on my problem:

I killed most processes on the plug and tested with hdparm:
hdparm  -tT /dev/sda4

/dev/sda4:
 Timing cached reads:    62 MB in  2.01 seconds =  30.92 MB/sec
 Timing buffered disk reads:    4 MB in  3.69 seconds =   1.08 MB/sec

I updated the kernel from sheeva-2.6.32.7-uImage to sheeva-2.6.34-uImage and hdparm gives the same results. I got the kernel from http://sheeva.with-linux.com/sheeva/

[joewein]

A speed of 1 MB/s (not Mb/s) may be expected if the device was recognized as a "full speed" USB device (up to 12 Mbps, the fastest supported by USB 1.1) instead of a "hi-speed" device (up to 480 Mbps, the fastest supported by USB 2.0)).

Do you use any kind of hub?

[dattaway]

I have setup my sheevaplug with ubuntu and root on the USB disk. The Disk is an 1Tb Iomega device.

What is the model number of this Iomega drive?

I had one of those before and had to take it apart and put a new USB controller on it.

[mgiann]

No, I don't use a hub. The drive is connected directly on the plug.

Regarding the drive:
lsusb
Bus 001 Device 002: ID 059b:0475 Iomega Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

hdparm -i /dev/sda

/dev/sda:
 HDIO_GET_IDENTITY failed: Invalid argument

hdparm -I /dev/sda

/dev/sda:

ATA device, with non-removable media
Standards:
        Likely used: 1
Configuration:
        Logical         max     current
        cylinders       0       0
        heads           0       0
        sectors/track   0       0
        --
        device size with M = 1024*1024:           0 MBytes
        device size with M = 1000*1000:           0 MBytes
Capabilities:
        IORDY not likely
        Cannot perform double-word IO
        R/W multiple sector transfer: not supported
        DMA: not supported
        PIO: pio0

sdparm  /dev/sda
    /dev/sda: ST310005  28AS
Read write error recovery mode page:
  AWRE        0
  ARRE        0
  PER         0
Caching (SBC) mode page:
  WCE         0
  RCD         0



However, the drive works at much higher speeds when connected to a laptop running openSuse 11.2.

I am also puzzled be these lines from syslogd:

Jun  3 00:20:36 papitsa kernel: Waiting 10sec before mounting root device...
Jun  3 00:20:36 papitsa kernel: usb 1-1: new full speed USB device using orion-ehci and address 2
Jun  3 00:20:36 papitsa kernel: usb 1-1: not running at top speed; connect to a high speed hub

Any ideas?

[joewein]

Jun  3 00:20:36 papitsa kernel: usb 1-1: new full speed USB device using orion-ehci and address 2
Jun  3 00:20:36 papitsa kernel: usb 1-1: not running at top speed; connect to a high speed hub

"Full Speed USB device" means a maximum of 12 Mbps, not the 480 Mbps supported by USB 2.0. That seems exactly the problem. It should be "Hi-speed USB device" for a USB 2.0 hard disk.

[mgiann]

I worked around the problem by connecting a usb Hub on the sheevaplug. The hub is a 4 port BELKIN mobile. Now syslog messages read:

Jun  5 12:15:55 papitsa kernel: Waiting 10sec before mounting root device...
Jun  5 12:15:55 papitsa kernel: usb 1-1: new high speed USB device using orion-ehci and address 2
Jun  5 12:15:55 papitsa kernel: hub 1-1:1.0: USB hub found
Jun  5 12:15:55 papitsa kernel: hub 1-1:1.0: 4 ports detected
Jun  5 12:15:55 papitsa kernel: usb 1-1.4: new high speed USB device using orion-ehci and address 3
Jun  5 12:15:55 papitsa kernel: scsi0 : usb-storage 1-1.4:1.0
Jun  5 12:15:55 papitsa kernel: scsi 0:0:0:0: Direct-Access     ST310005 28AS                  PQ: 0 ANSI: 2 CCS

and hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   576 MB in  2.00 seconds = 287.87 MB/sec
 Timing buffered disk reads:   94 MB in  3.04 seconds =  30.90 MB/sec


Still, I would like to know why the drive is that slow when connected directly to the plug.

Can we move this thread to the kernel subforum, as it seems to be more relevant?