External USB Drives in Linux

Adding external USB drives in Linux is easy. Etch uses hotplug to detect it. Using dmesg you can find out what mountpoint it is (Linux creates a SCSI device to mount to /dev/sdb and the drive will probably be /dev/sdb1).

/proc/bus/usb/devices shows you information about the connected USB device.

Most USB devices are formatted FAT32 which has a file size limit of 4GB. Because I'm using mine for Netvault backups and the virtual library media is created at sizes much larger than that, there are 2 choices:

ntfs-3G (which Etch doesn't support) and ext3 (which etch does).

Format to ext3 using

mke2fs -T ext3 /dev/sdb1

Then create an /etc/fstab entry

and mount

Test the (unmounted) disk for bad blocks and write garbage all over each block using

badblocks -c 10240 -s -w -t random -v /dev/sdb

(nb. it's better to use dd if=/dev/urandom of=/dev/sdb but takes much much longer...)

In order to encrypt the whole disk I used this tutorial [1]

apt-get install cryptsetup hashalot

cfdisk /dev/sdb (if you still need to partition the disk, unlikely though)

cryptsetup --verbose --verify-passphrase luksFormat /dev/sdb1

Open the encrypted device and assign it to a virtual /dev/mapper/YOURNAME device:

cryptsetup luksOpen /dev/sdb1 YOURNAME

mkfs.ext3 -m 1 -O dir_index,filetype,sparse_super /dev/mapper/YOURNAME

To mount

mount /dev/mapper/YOURNAME /mnt/

Now it's transparently encrypted

To unmount

umount /mnt/YOURNAME

cryptsetup luksClose /dev/mapper/YOURNAME