Managing Disk Space on the Lab Suns

Finding Current Disk Usage with df

You can find all the mounted file systems space usage by typing:

df -k

An excerpt from the output of df -k looks something like this:

Filesystem	kbytes	used	avail	capacity	Mounted on
/dev/dsk/c0t0d0s0	1984230	1791665	133039	94%	/
/dev/dsk/c0t0d0s3	6484885	1607988	4812049	26%	/space
piemonte.eecs.uic.edu:/usr/local	2597102	1482135	1063025	59%	/usrlocal
piemonte.eecs.uic.edu:/backup/monviso	15441539	10071320	5215804	66%	/backup

The headings are:

Filesystem

The actual location of this file system. A notation like /dev/dsk/c0t0d0s3 means it is on local disk number 0, partition number 3. A notation like piemonte.eecs.uic.edu:/usr/local means it is on piemonte, at the designated path, and we have mounted it remotely via nfs.

kbytes

The size of the file system in k-bytes

used

what you think

avail

kbytes - used

capacity

used ÷ kbytes, percentage that is in use. This can exceed 100%, because unix filesystems sometimes have a little extra capacity above the official limit

Mounted on

The mount point on the local filesystem

The above example shows that 5.2 GB are available on the /backup filesystem. Usually 2-3 GB is needed for a backup file.

Notice that for nfs-mounted files, the local filesystem path (e.g. /usrlocal or /backup ) does not have to match the filesystem path on the file's home computer.

Why You Almost Always Use df -k Instead of plain df

• The plain command df gives sizes in blocks on some machines, k-bytes on others.
  df -k guarantees you will see k-bytes.
• The UCB and System V versions of the df command usually show different information, and in different formats.
  Both versions of df are installed on Solaris, the one you get will depend on your path.
  df -k gives the same output from both versions.
  

Checking the space occupied by directories

Sometimes, you will need to check the space occupied by all the subdirectories of a certain directory (for example, because you want to know the directory that is occupying most space. You can use the command du in a form like:

du -kd

this will list the space occupied by all directories and their subdirectory from the current position. For more info see the man pages.

More to come

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Last Revised: 24 May 2003
Riccardo Serafin