Performance problems with external USB drive

[Sasha Tsykin]

Matthias wrote:

> Hi,
>
> I have an Samsung laptop which boots a kubuntu (breezy) from an 
> external usb drive.
> This drive is usb 2.0 capable and so are two of the four laptop usb 
> controllers.
> However, this drive is very slow here [0]. I noticed that the drive is 
> much faster when it is connected to a knoppix installation on another 
> computer of mine. Unfortunately I cannot test this again at the moment 
> as I don't have access right now to the other computer.
> It was also slow when I connected it to the laptop when it was booted 
> from the internal drive, so I think it does not matter, that the whole 
> system is now booting from this external drive.
>
> I did research in several Ubuntu-forums and mailing lists but only 
> found suggestions regarding async/sync and usb 1.1/2.0.
> Afaik ~8mb is significantly more than what usb 1.1 is capable of, so I 
> think v2.0 is used.
> mount [1] tells me nothing of async but I included it in /etc/fstab 
> [2]. I also did mount -o remount,async on /dev/sdaX and 
> /dev/mapper/crypto* respectively but it doesn't change anything. Why 
> does async not appear?
>
> As some users with similar problems suggested to check whether the 
> right kernel moduls are loaded (ehci_hcd is the first to load 
> etc)...this seems to be correct here as well.
>
> Does anyone have an idea what I can test next? I also included the 
> shortened output of /proc/bus/usb/devices [3] and dmesg [4].
>
> Any help is very appreciated!
>
> Regards,
> Matthias
>
> P.S.: I cannot find this thread right now but iirc there was a similar 
> problem that I heard of, when some daemon was running and KDE was 
> used. The solution there was to simply shut down that daemon but I 
> even can't remember where I read it...
>
> [0] # hdparm -tT /dev/sda
> /dev/sda:
>  Timing cached reads:   1288 MB in  2.00 seconds = 643.78 MB/sec
>  Timing buffered disk reads:   24 MB in  3.01 seconds =   7.97 MB/sec
>
> [1] # mount
> /dev/sda2 on / type reiserfs (rw,noatime,notail)
> proc on /proc type proc (rw)
> usbfs on /proc/bus/usb type usbfs (rw)
> /dev/mapper/cryptohome on /usr type reiserfs (rw,noatime)
> /dev/sda4 on /media/sda4 type reiserfs (rw,noatime)
>
> [2] # cat /etc/fstab
> <file system> <mount point>   <type>  <options>       <dump>  <pass>
> /dev/sda2 / reiserfs         notail,async,noatime    0       1
> /dev/mapper/cryptohome /usr     reiserfs async,noatime  0       2
> /dev/sda4 /media/sda4 reiserfs     async,noatime           0       2
> /dev/mapper/cryptoswap none swap sw,async,noatime    0       0
>
> [3] # cat /proc/bus/usb/devices
> T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=480 MxCh= 0
> D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=0d49 ProdID=3100 Rev=77.f8
> S:  Manufacturer=Maxtor Corporation
> S:  Product=Personal Storage 3100
> S:  SerialNumber=508010009519
> C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=100mA
> I:  If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
>
> [4] # dmesg
> [4294670.038000] ehci_hcd 0000:02:06.2: USB 2.0 initialized, EHCI 
> 1.00, driver 10 Dec 2004
> [4294670.067000] ohci_hcd: 2004 Nov 08 USB 1.1 'Open' Host Controller 
> (OHCI) Driver (PCI)
> [4294670.266000] usb 1-1: new high speed USB device using ehci_hcd and 
> address 2
>
It is possible your laptop has USB full speed not USB Hi Speed. USB Full 
Speed is actually USB 1.1 rebranded, but is used for marketing purposes. 
If access to the drive is very slow, that might be the problem.

Sasha