slow USB disk writes

[Karl Auer]

Hi all.

I'm currently backing up about 80GB of data to an external USB drive, a
fairly new 1TB HDD in a USB2.0 enclosure that is reported as a
"high-speed device" in my logs:

Dec 13 23:34:32 karl kernel: [455208.469135] usb 1-3: new high speed USB device using ehci_hcd and address 8
Dec 13 23:34:32 karl kernel: [455208.604989] usb 1-3: configuration #1 chosen from 1 choice
Dec 13 23:34:32 karl kernel: [455208.607216] scsi9 : SCSI emulation for USB Mass Storage devices
Dec 13 23:34:37 karl kernel: [455213.610623] scsi 9:0:0:0: Direct-Access     WDC WD10 EARS-00Y5B1           PQ: 0 ANSI: 2
Dec 13 23:34:37 karl kernel: [455213.611998] sd 9:0:0:0: Attached scsi generic sg2 type 0
Dec 13 23:34:37 karl kernel: [455213.613072] sd 9:0:0:0: [sdb] 1953525168 512-byte hardware sectors: (1.00 TB/931 GiB)
Dec 13 23:34:37 karl kernel: [455213.615354] sd 9:0:0:0: [sdb] Write Protect is off
Dec 13 23:34:37 karl kernel: [455213.623000]  sdb: sdb1
Dec 13 23:34:37 karl kernel: [455213.634903] sd 9:0:0:0: [sdb] Attached SCSI disk
Dec 13 23:34:38 karl kernel: [455214.737309] kjournald starting.  Commit interval 5 seconds
Dec 13 23:34:38 karl kernel: [455214.738442] EXT3 FS on sdb1, internal journal
Dec 13 23:34:38 karl kernel: [455214.738451] EXT3-fs: mounted filesystem with writeback data mode.

I say "currently" because it has been running for about 24 hours and is
about three-quarters done. Call me picky, but this seems slow to me.

USB2 should be able to do 30MB/s on a clear day with a fair wind and all
the stars in the right positions. That's 30 gigabytes in about a
thousand seconds, but let's say 15 minutes. Allow for my system to be
running at a tenth of that, thirty GB would take 150 minutes, but let's
say three hours. My 80GB should have taken no more than about eight
hours, even by that pessimistic calculation.

The USB drive is formatted with ext3 and is mounted in "writeback" mode.
Below is what lsusb says about the device. The packet size looks a bit
sad, but maybe it's not what I think it is.

How fast can other people write 80GB to an external USB2.0 HDD? Looking
for actual experience here, not theories :-)

Regards, K.

Bus 001 Device 008: ID 04fc:0c25 Sunplus Technology Co., Ltd 
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x04fc Sunplus Technology Co., Ltd
  idProduct          0x0c25 
  bcdDevice            1.12
  iManufacturer           2 Sunplus Technology Co.,Ltd.
  iProduct                3 USB to Serial-ATA bridge
  iSerial                 1 FDC0FD10EA00000FD0FCAF5C560137
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           32
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          4 Bulk Only Configuration
    bmAttributes         0xc0
      Self Powered
    MaxPower                2mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     80 Bulk (Zip)
      iInterface              5 Bulk Only Interface
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  bNumConfigurations      1
Device Status:     0x0001
  Self Powered

 
-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)                   +61-2-64957160 (h)
http://www.biplane.com.au/kauer/                   +61-428-957160 (mob)

GPG fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687
Old fingerprint: B386 7819 B227 2961 8301 C5A9 2EBC 754B CD97 0156
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
URL: <https://lists.ubuntu.com/archives/ubuntu-users/attachments/20101214/3d2e2d2a/attachment.sig>