Mounting a USB disk in a permanent location

Question

I have a USB hard disk that I want to mount on boot and in a specific location. How can I make that drive mount and stay available (say for local backups, etc.) even though no one's logged in?

It seems that udev or something similar grabs hold of the disk. If I put an entry in /etc/fstab that tries to specifically mount this disk (by UUID), then that mount process and the udev mount process seem to end up in a battle with each other and the disk doesn't get mounted.

Answer 1

Mount the disk using udev. Place the rules from this wiki into /etc/udev/user.rules and reboot (or reconnect the USB HDD) . There are several favors of rules in the wiki (that's why I didn't list them here), choose the one that best suits your needs (e.g. you need a specific normal user to be able to unmount it).

Perusing /lib/udev/rules.d/80-udisks.rules will help you understand what's udev doing to your hard disk.

Besides the udev rules I mentioned above I think there's another approach you can take: instruct udisks (through udev) to leave your disk alone and then mount it through fstab.

This code works on my system

ACTION!="add|change", GOTO="my_udisks_end"
SUBSYSTEM!="block", GOTO="my_udisks_end"

ENV{ID_TYPE}!="disk", GOTO="my_udisks_end"
ENV{ID_BUS}!="ata", GOTO="my_udisks_end"
ENV{DEVTYPE}!="partition", GOTO="my_udisks_end"

KERNEL=="sd*|hd*", ENV{UDISKS_PRESENTATION_NOPOLICY}="1"

LABEL="my_udisks_end"

but is generic and includes all partitions. To be able to target your particular hdd/partition use udevadm info --query=all -n /dev/sdX and then match on some of those particular atributes in the udev rules.

A good resource to help you in this is Writing udev rules. Unfortunately it contains some outdated info (udevinfo was replaced by udevadm indo). I assure you, though, it's a worthwhile read -- udev is a central piece of architecture nowadays and you can accomplish a lot by using it. It's also pretty flexible.

It's also easy to make mistakes in udev rules :). Use udevadm test $(udevadm info -q path -n /dev/sdX) to take a 'peek' at what's udev doing.

Answer 2

You could try referencing it by /dev/... instead of by UUID. It is most likely /dev/sdb*, you can check this by going to System -> Administration -> System Monitor and clicking on the 'File Systems' tab. You will need to have inserted the USB drive first and let it be automatically mounted. Replace 'UUID=uuid' with the '/dev/sdb*' in /etc/fstab. It's always a good idea to back up fstab before editing it.