Re: Problem with an external usb HD - slow usb

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Hi list and Patrick,

the default max_sectors is 240. I change this to 1024 like you said but the problem continue.

If i try the speed:

time dd if=/dev/sdc1 of=/dev/null bs=1M count=5
i get that speed: 972 MB/s

but if i run rsync, the upload transfer rate is very slow ( begins at 4MB/s and goes below until 0.7KB/s)

[]'s
Luigi Castro Cardeles


2010/3/6 Patrick O'Callaghan <pocallaghan@xxxxxxxxx>
On Sat, 2010-03-06 at 11:05 -0300, Luigi Castro Cardeles wrote:
> Hi list,
>
>
> I use fedora 12 on a dell inspiron 1545 laptop.
> (2.6.31.12-174.2.22.fc12.x86_64).
> i have a external usb hd and i can't make it connect like a usb 2.0
> device.
> this device is ntfs format
>
>
> I check if the device is using ehci (dmesg after i plug the device)
> [root@localhost ~]# dmesg | grep USB
> usb 2-2: new high speed USB device using ehci_hcd and address 2
>
>
> I check if this device is connected on a usb 2.0
> [root@localhost ~]# lsusb
> Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
> Bus 002 Device 015: ID 0471:2021 Philips
> Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
>
>
> I mount the device with this options:
> /dev/sdc1 on /media/hd_backup type fuseblk
> (rw,nosuid,nodev,allow_other,blksize=4096)
>
>
> but when i use cp, mv or rsync, the max speed i get is max 6MB/s (a
> lot 800kB/s).
> If i use this device on Windows (tested with Vista and Seven), i get
> much high transfer rate.
> I read about sync and async options, but if i put sync or async on
> fstab, it does not alter the transfer rate.
>
>
> Is this the normal upload transfer rate? I am doing something wrong?

Try this as an experiment:

echo 1024 > /sys/block/sdc/device/max_sectors

and repeat your I/O measurement.

poc


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