Linux Server Hacks, Volume Two

Hack #51. Free Up Disk Space Now

Moving large files to another partition isn't always an option, especially if running services are holding them open. Here are a few tips for truncating large files in emergency situations.

Server consolidation takes planning, and it usually means adjusting the way you set up your OS installations. Running multiple services on a single OS image means not only increased network traffic to the same hardware, but increased disk usage for logfiles.

What's more is that administrators' thirst for more data about the services they run has resulted in a tendency for logging to be more verbose these days than it was in the past, partially because the tools for analyzing the data are getting better.

However, someday you'll inevitably be faced with a situation where you're receiving pages from some form of service monitoring agent telling you that your web server has stopped responding to requests. When you log in, you immediately type df –h to see if what you suspect is true, and it is—your verbose logging has just bitten you by filling up the partition, leaving your web server unable to write to its logfiles, and it has subsequently stopped serving pages and become useless. What to do?

There are several commands you can use to deal with this. If the service is completely dead, you could actually move the file to another partition, or simply run rm -f logfile if you know that the data is not particularly useful. If the service is still running, however, and needs ...