how can I fix a partition

Hi,
problem: Booting the Dockstar with a usb-hd attached (and a stick) sometimes mount the stick to /dev/sda1 and sometimes to /dev/sdb1.

How can i fix the stick or the hd to a fix partition name?

Greetings,
Thomas

Hi Thomas,

I've just been looking into that today :)

I've used custom udev rules to do this.

An example:

I created a file named /etc/udev/rules.d/custom.rules containing:

KERNEL=="sd*[0-9]", ATTRS{product}=="Flash Disk", SYMLINK+="usb%n"
KERNEL=="sd*[0-9]", ATTRS{product}=="StorE HDD", ATTRS{serial}=="201005260571",SYMLINK+="nas_main"
KERNEL=="sd*[0-9]", ATTRS{product}=="StorE HDD", ATTRS{serial}=="2010052627E8",SYMLINK+="nas_backup"

This means my usb sticks always mount to /dev/usb%n.
And my two USB drives that I'm using as my NAS and NAS backup are mounted as /dev/nas_main and /dev/nas_backup.
I plan to rsync or duplicity those, so use the serial to distinguish between them.

To find the appropriate attributes, to do the filtering on for my disks, I used this command to list all the attributes

udevadm info --name=/dev/sda1 --attribute-walk

More info about udev I found on http://wiki.debian.org/udev

I've also used autofs to mount these automagically. But note that there is a bug in ntfs-3g which means auto-mounting ntfs drives with autofs fails unless you remove the mtab symlink to /proc/mounts. Took me a while to figure out. This is due to a bug which is not yet fixed in the ntfs-3g version on debian squeeze. Basically autofs passes a -n flag to mount when the mtab is symlinked, and ntfs-3g falls over when passed the -n flag.

Cheers,
Menno



Edited 1 time(s). Last edit at 10/28/2010 09:08PM by menno.

Hi Thomas,

Just to update I found some further info on this.

You can also list devices by label or by uuid (eg 'ls /dev/disk/by-label)

You can set the label using tune2fs -L and mkswap -L

Then you can use the label in fstab directly by mounting with the label by using /dev/disk/by-label/your_label

Or you can reference the label in udev rules using ENV{ID_FS_LABEL}

Note that oddly the UUID is not unique on disks. My two USB external hard disks, identical models, both use the same UUID, duh.

Cheers,
Menno