Moving /usr

When I set up my hard drive to take Debian, I didn’t take into account the vast range of software that I was going to find immediately indispensible. So, /usr was on the same partition as /, and it was taking up 1.1 Gb of a 2 Gb partition. That was unsupportable, of course, so I had to move /usr to it’s own wee data fiefdom.

I’ve moved /home a few times, and I have a procedure for that, but I wasn’t sure you could do the same thing with /usr. I asked Arthur, and he pointed out something very important – the editiors are on /usr, and so I had to edit /etc/fstab before renaming /usr. Once I had the order worked out though, it went perfectly. Here is the procedure:

# Set up a partition table on the new hard drive
cfdisk /dev/hdb

# Get a filesystem on the partition
# you're going to use
mkfs.ext2 /dev/hdb1

# Mount the soon-to-/usr partition
mount /dev/hdb1 /mnt/tmp/

# Edit the filesystem table
vi /etc/fstab
# Add the new /usr to the table
/dev/hdb1   /usr    ext2    defaults   1   2

# Get into /usr and prepare to copy
cd /usr

# Single-user mode
# a bare root for low-level maintenance
init 1

# Copy everything into the new /usr
cp -ax * /mnt/tmp/

# Rename /usr so that you can mount
# the new /usr in the right place
mv /usr /usr.old

# Set up the mount point
mkdir /usr

# Cross your fingers