One important responsibility of the system administrator is ensuring that there is adequate disk space for the users. To do this, you must monitor the free space in each filesystem and take corrective action whenever free space gets too low. The amount of free space depends on the size of the disk containing the filesystem and the number of files on the disk. To determine how much free space is available in a filesystem, see ``Displaying filesystem and directory usage statistics''.
A UNIX system operates best when at least 15% of the space in each filesystem is free. If a filesystem has less than 15% free space, system operation typically becomes sluggish.
When a filesystem has little or no space left to work, the system displays the following:
NOTICE: Out of space on EAFS dev hd (major/minor)When the filesystem runs out of space, the system stops any attempts to write to the filesystem. (The error message list the filesystem by its major and minor device numbers, for example hd(1/42) for the root filesystem.) The only way to restore system operation is to delete or reduce files from the named filesystem.
If the free space falls below 15%:
By default, cron clears out the /tmp and /usr/tmp directories once each day. You can define which directories and how often they are cleared in the /etc/default/cleantmp file. See the cleantmp(ADM) manual page.
You can include a reminder in the /etc/motd (message of the day) file, send e-mail, or send a message to the terminals of all users currently logged in. See the mail(C) and wall(ADM) (``write to all'') manual pages.
See Finding files of a certain size.
See ``Finding temporary files''.
``Checking and clearing system log files''.
For example, delete data in the /usr/adm, such as the sar data in the /usr/adm/sa directory or, if accounting is enabled, the data in the /usr/adm/acct directory.
Back up these files using the Backup Manager before removing them. See ``Running unscheduled filesystem backups''.
See the compress(C) manual page.
See ``Adding disk space and restructuring filesystems''.
See ``Creating filesystems on virtual disks''.