One day I came in to work and found that our development server - a Ubuntu box had a full hard disk. I did a bit of investigation using the du command and it seems like mozilla thunderbird is the major culprit. After burning off some backups, the disk was left at 94%:

$ df -h
Filesystem            Size Used Avail Use% Mounted on
/dev/sda1             895G  791G   59G  94% /
none                  4.0G  300K  4.0G   1% /dev
none                  4.0G  1.4M  4.0G   1% /dev/shm
none                  4.0G  140K  4.0G   1% /var/run
none                  4.0G     0  4.0G   0% /var/lock
none                  4.0G     0  4.0G   0% /lib/init/rw
$ cd
$ du -ch | grep [0-9]G
666G    ./.thunderbird/ccsmcruu.default/ImapMail/mail.adofms.com.au
666G    ./.thunderbird/ccsmcruu.default/ImapMail
667G    ./.thunderbird/ccsmcruu.default
667G    ./.thunderbird
2.2G    ./.VirtualBox/Machines/iBike/Snapshots
2.2G    ./.VirtualBox/Machines/iBike
2.2G    ./.VirtualBox/Machines
2.2G    ./.VirtualBox
670G    .
670G    total

I did some reading and found that Mozilla Thunderbird does not compact files by default - i.e. all of the old emails that were sent to trash are still kept. One of the mailboxes used to get a lot of spam so I guess this accounts for the 667GB. I opened up Thunderbird to see how much space the inbox actually takes up and it turns out to be approximately 500MB - over 1000 times less than the stuff that has not been compacted over the years.

So i right clicked on the inbox directory in the tree on the left of Thunderbird and selected 'compact'. I left it for about 12hours but even after that it still said 'compacting folder' on the status bar. I don't use Thunderbird on this PC - it belonged to a colleague who has left the company, however I do occasionally need to look through the inbox for references to the project I am working on, so deleting all traces of Thunderbird is not an option.

My question is - is there any way I can monitor the progress of Thunderbird's compacting function? I would really like to know how long it is going to take. Also is there any way I can speed up the compacting process?