Managing Disk Space

• People tend to forget about files they no longer use. Outdated files often stay on the system much longer than necessary.

• Some files, particularly log files such as /var/adm/SYSLOG, grow as a result of normal system operations. Normally, cron rotates this file once per week so that it does not grow excessively large. (See /var/spool/cron/crontabs/root.) However, you should check this file periodically to make sure it is being rotated properly, or when the amount of free disk space has grown small.

• The lost+found directory at the root of EFS filesystems may be full. If you log in as root, you can check this directory and determine if the files there can be removed.

• Some directories, notably /tmp, /usr/tmp, and /var/tmp, accumulate files. These are often copies of files being manipulated by text editors and other programs. Sometimes these temporary files are not removed by the programs that created them.

• The directories /usr/tmp, /var/tmp, and /var/spool/uucppublic are public directories; people often use them to store temporary copies of files they are transferring to and from other systems and sites. Unlike /tmp, they are not cleaned out when the system is rebooted. The site administrator should be even more conscientious about monitoring disk use in these directories.

• Users move old files to the dumpster without realizing that such files are not fully deleted from the system.

• vmcore and unix files in /var/adm/crash are accumulating without being removed.

• Binary core dumps, core files, from crashed application programs are not being removed.

Tip: The section "Freeing Up Disk Space" in Chapter 6 of the Personal System Administration Guide provides additional ideas for identifying unnecessary files. The following subsections describe various techniques for monitoring disk space usage, locating unneeded files, and limiting disk usage by individual users.

Monitoring Free Space and Free Inodes

Monitoring Key Files and Directories

Cleaning Out Temporary Directories

Locating Unused Files

Identifying Accounts That Use Large Amounts of Disk Space

Running Out of Space in the Root Filesystem

Imposing Disk Quotas

Monitoring Disk Quotas