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Re: External USB Hard-Drive on Linux

On Wed, 8 Mar 2006, Martin Gregorie <see@xxxxxxxxxxxxxx> wrote:-


Here's my experience using SUSE 9.3 and an external 3.5" 80GB WD drive,
which cost me all of £50 due to being on sale at Staples last summer.
Since SUSE 10.0 seems to work the same when using a 20GB drive in a
similar configuration, there shouldn't really much in the way of

>- when I first connected it I was logged in as root with tail on the
>log so I could see what went on. The drive was recognized, a directory
>(WD_USB_2) was added to /media

Same here. The directory WD_USB_2 is created under /media, whereas the
no-name enclosure with a 2.5" 20GB Toshiba drive just gets usbdisk.

>and the drive was mounted on it.

This is different. The mount point is created but the drive isn't
mounted straight away. It's only when a user, normal or root, looks in
the directory that the drive is auto-mounted by submountd. As long as
someone is looking in the directory, e.g. a window is open to look at
the contents, or a shell is open with the directory as (part of) the
current path, the drive stays mounted. After the last access to it, it's
no longer part of someone's CWD, or the directory window is closed,
submountd waits for about three seconds and then unmounts the drive.

Another thing that I've noticed is that if the drive is in use by a
normal user and then I use FTP to transfer files from one machine to
that drive, they fail because of a permissions problem. For some reason,
the files take on a root.users ownership and stay that way until it is
unmounted. Once it's unmounted, I can remount it as a normal user and
the files take on my $UID.users ownership.

>I think the mount directory name is made from the drive maker
>abbreviation (Western Digital) plus the USB port (USB_1 or USB_2 - I
>have the drive in the bottom port of two.

Maybe, although that doesn't explain the 20GB drive being given the
mount-point usbdisk. I wonder if the "WD_USB_2" is a part of the
identifier string.

>- logging out unmounts the drive, which times out and stops after a while.

Since submountd unmounts the drive when the last user stops using it, I
would assume this would happen with my drive. However, as I use mine as
a "temporary" storage expansion for my home directory, it's always in
use and I don't know if the drive would spin down or not.

>- logging in spins it up and mounts the drive on the same directory.

My guess would be a similar thing occurs with SUSE. Can't say for
certain since it's been a while since I logged in. Using VNC over my
network, I've been logged in for about a couple of months.

>- ssh login does not spin up or mount the drive. Nor does running a
>script. As long as the drive is connected and powered on, the act of
>mounting it spins it up. Umounting it causes it to time out and stop.

Testing using my 20GB drive on SUSE 10.0, running a script does mount
the drive. I don't know about spinning up the drive as it's a quiet
drive and the cooling fans here make a bit too much noise to hear it
unless the enclosure is pressed against my ear.


>- I reckon that as long as the drive is spun down its contents are
>pretty safe from anything short of a house fire regardless whether its
>powered on or not. So the drive just sits on the system box,
>permanently  connected and permanently powered on.

Well, unless the machine is connected to a wired network and ADSL, and
there's a nearby lightening strike that fries all the machines on the
network, it's probably fine.

>As I said, this is what happens with FC4 and Gnome, but I'd imagine
>that SUSE
>will do pretty much the same.

Pretty much so. There appear to be minor differences but it's basically
the same.

  David Bolt

Member of Team Acorn checking nodes at 50 Mnodes/s: http://www.distributed.net/
AMD1800 1Gb WinXP/SUSE 9.3  | AMD2400 256Mb SuSE 9.0  | A3010 4Mb RISCOS 3.11
AMD2400(32) 768Mb SUSE 10.0 | RPC600 129Mb RISCOS 3.6 | Falcon 14Mb TOS 4.02
AMD2600(64) 512Mb SUSE 10.0 | A4000 4Mb RISCOS 3.11   | STE 4Mb TOS 1.62

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