Setting up External Hard Drive (USB) as a backup system on Slack 12.0

thethinker · 12-16-2008, 10:41 AM

Hey everyone,
I recently got a USB external hard drive for use as a backup system. Now, I am using this hard drive as a backup for a windows computer as well. Basically all I can do right now is mount it (using mount /dev/sdb1 /mnt/tmp) and see the windows file system, but not write to it. So there are a few things I need to know how to do:

1) Make a linux partition (ext2 I suppose) on the harddrive that I can write to...is fdisk the way to go?

2) Make it so that when my computer boots up, if the hard drive is connected it automatically mounts (this is something in fstab obviously, but I know there is some kind of problem with naming sda1,sdb1, etc...how can I make sure the computer can find the linux partition every time? Is there a unique name somewhere I can use, or I've heard about "udev rules" as well...)

3) Some advice on permissions for this kind of process...ie if I am running backups every week or so, should I just keep the hard drive on root permissions, or maybe user-read only or something?

I don't need to many details, mostly just commands to use so I can start doing some web searching.

Thanks a bunch guys.

titopoquito · 12-16-2008, 10:57 AM

http://reactivated.net/writing_udev_rules.html about persistent disk names, so that you can create /dev/exthd or whatever.
A sample line from my laptop:

Code:

# freecom external harddisk
BUS=="usb", KERNEL=="sd*", ATTRS{serial}=="152D20336012", NAME="%k", SYMLINK="freecom%n"

You don't necessarily need a Linux partition on the disk. NTFS or FAT32 are fine, too. For NTFS you will need ntfs-3g installed (take a slackbuild script from 12.1/12.2 or from http://www.slackbuilds.org .
You only have to look at "umask" to make the partition writable for you as normal user (if you want that).

thethinker · 12-16-2008, 02:19 PM

ok cool thanks for the reply...I've got ntfs-3g on my system already, so that should be fine, but I tried to assign my hard drive a rule via udev and failed. I used

Code:

BUS=="usb", KERNEL=="sd*", ATTRS{size}=="976773168", NAME="%k", SYMLINK="exthd%n"

But here is the kind of link is creates:

Code:

# ls /dev/exthd*
/dev/exthd@
# file /dev/exthd
/dev/exthd: symbolic link to `sdb'

so it makes a link to sdb, not sdb1 or whatever. I know that sdb1 is what I want to try to mount, so how do I incorpoerate that into the rule? I figured the "%n" on the SYMLINK command would make that happen. Any ideas?

titopoquito · 12-16-2008, 02:24 PM

Sorry, I'm clueless. It creates symbolic links here too, but also to the partition itself.

Code:

$ ls -alh /dev/freecom*
lrwxrwxrwx 1 root root 3 2008-12-16 21:22 /dev/freecom -> sdc
lrwxrwxrwx 1 root root 4 2008-12-16 21:22 /dev/freecom1 -> sdc1

Have you restarted udev? I guess so, else it wouldn't have picked up the rule anyway ...

JazzItSelf · 01-06-2009, 03:06 PM

I'm not sure if ntfs-3g has done this differently or not, but the windows implementation of NTFS has (or had) some issues regarding storing dates in UTC, but ignoring daylight savings. This could add or subtract an hour here or there... or something like that.

I don't know if that's still the case, I don't know if ntfs-3g does it that way or not, and I don't even know if that would be important to you! I've seen it cause issues for people in the past, so I figured I'd throw it out as a heads up.

--Cp