document shrinking LVMs

        mount /srv

        service apache2 start

# Shrinking

 1. unmount the filesystem:

        umount /mnt

    If that's not possible because the filesystem is in use, you'll

    need to stop processes using it. If that's possible (for example

    when resizing `/`), you'll need to reboot in a separate operating

    system first.

 2. forcibly check the filesystem:

        e2fsck -fy /dev/sdX

 3. shrink the filesystem:

        resize2fs /dev/sdX 5G

 4. shrink the logical volume, to reduce *to* 5G:

        lvreduce -L 5G vg/mnt

    to reduce *by* 5G:

        lvreduce -L -5G vg/mnt

    WARNING: make sure the resulting size matches exactly the one

    specified in the `resize2fs` command above.

 5. tell ext to resize the filesystem *again*:

        resize2fs /dev/sdX

    NOTE: no size argument here!

 6. check the filesystem again:

        e2fsck -fy /dev/sdX

 7. if you want to resize the underlying device (for example, if this

    is a LVM inside a virtual machine on top of another LVM), you can

    also shrink the parent logical volume, physical volume, and crypto

    device (if relevant) at this point.

        lvreduce -L 5G vg/hostname

        pvresize /dev/sdY

        cryptsetup resize DEVICE_LABEL

    WARNING: this last step has not been tested.