The df command

About the df command

To verify the amount of free disk space on the filer, enter the df command on the filer. Information generated from the df command is also available through SNMP, using the Network Appliance custom MIB, which is described in "About the Network Appliance custom MIB."

With the -i option, the command displays the number of used inodes and the number of available inodes. Following is an example of the df -i command:

df -i /vol/home

Filesystem    iused      ifree    %iused   Mounted on

/vol/home/    240843     121525     66%     /vol/home

The total amount of disk space shown in the df output is less than the sum of available space on all disks installed in the volume. Consider the following sample df command issued on a volume with seven 2-GB disks installed:

df /vol/vol0

Filesystem          kbytes    used       avail   capacity

/vol/vol0/          9886448   8426196    1460252 85%

/vol/vol0/.snapshot 1098492   427008     671484  39%

When you add the numbers in the kbytes column, notice that the sum, 10,984,940 KB (about 11 GB), is significantly less than the total disk space installed (14 GB). The following reasons account for the discrepancy:

The parity disk, which is a 2-GB disk in this example, is not reflected in the output of the df command.
As with the UNIX FFS (Fast File System), the filer reserves 10 percent of the total disk space for efficiency, which df does not count as part of the file system space.

The filer doesn't limit the size of a file system. The maximum size of the file system is restricted only by the amount of disk space installed in the volume. For individual files, the maximum size is 8 TB. Many NFS clients restrict the file size to 2 GB or 4 GB.

Using the df command with qtrees

When you enter a df command with a path name on a client, the command returns the amount of free space in the file system containing the path name. For example, if the filer is mounted on the client as /t/toaster, the df command on the client displays the disk information about the /t/toaster file system as follows:

df /t/toaster/engineering/jdoe

Filesystem            kbytes    used   avail capacity  Mounted on

toaster:/            2097151 1646923  450228    79%    /t/toaster

However, if you defined qtrees on the filer, the information about available space could be misleading because the actual space available might be less. For example, if /engineering is a qtree with a disk quota of 1,800 MB, the space available in the /t/toaster/engineering directory is less than that in the df command output shown in the preceding example.

If you have qtrees on the filer, Network Appliance recommends that you mount each qtree separately. For example, if the filer named toaster has two qtrees, /vol/home/engineering and /vol/home/marketing, mount toaster:/vol/home/engineering and toaster:/vol/home/marketing on two mount points, for example, /t/toaster/engineering and /t/toaster/marketing.

In this way, the filer takes the qtrees into consideration when responding to a df command from a client and returns the amount of free space in each qtree, as opposed to the space available in the entire file system.

Part No. 210-02334
File: quota3.htm
Last updated: 02/24/99 12:16:58