Recovering lost disk space with DF and DU

So, you're running a Debian Linux server and all is going well. Suddenly, Bang! everything breaks, clients start calling asking about their email, your websites are down! Overnight your hard drive has filled up.

So how do to go about fixing this? (Note, though these instructions are tailored to Debian, they should work similarly for any flavour of Linux)

Well, the first thing to do is to find out if your hard drive is full. get a command line up and type:

You should see something like this:

Filesystem           1K-blocks      Used Available Use% Mounted on

/dev/hda1               255912    147070     95189  61% /

tmpfs                   242272         0    242272   0% /dev/shm

/dev/hda9             69402812    901484  64975868   2% /home

/dev/hda8               369000      8495    340845   3% /tmp

/dev/hda5              4807056    561116   4001756  13% /usr

/dev/hda6              2885780   1432464         0 100% /var

tmpfs                    10240       692      9548   7% /dev

Here we can see that the hda6 partition is full, in other words my /var directory. This is a good first step, but which files are using the space. Type:

You should see something like this:

713420  www

327916  log

180960  cache

142380  lib

776     backups

632     mail

576     spool

112     run

48      lost+found

12      named

8       tmp

8       lock

8       local

4       opt

So most of my drive space is being used by the www directory, in other words my websites. Now we need to find out specifically which files are taking up the space so type:

This will give you a list of all the files larger than 50 MB. You should get a list of large files in the /var directory. This is pretty helpful. Any large log files? these are safe to delete. Any big tar.gz files you're not using? Get rid of all the crap.

You can automate this deletion if you're feeling very brave. IMPORTANT: Only do this if you're absolutely sure what you're doing! It will delete any files over 100MB in size without warning! If you're certain you don't need them type:

IMPORTANT. Again, Check first that you dont need any of the big files! If you're in doubt do this manually.

Now do another:

and there, lots of free space for you to fill up all over again. One point, if you've deleted log files you may need to restart your services to recreate them, so for example if you're running apache2 and you've deleted apache logs you might need to do:

The same goes for postfix, etc.

As a final step you might want to set up a cron job to email your disk usage stats to you every day or so so type

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Last Updated ( Thursday, 16 August 2007 )