Ascertaining free disk space

Command for ascertaining free disk space

You use the df command to verify the amount of free disk space on the filer.

Disk space report discrepancies

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, the sum, 10,984,940 KB (about 11 GB), is significantly less than the total disk space installed (14 GB). The following causes 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.
Like the UNIX FFS (Fast File System), the filer reserves 10% of the total disk space for efficiency, which df does not count as part of the file system space.
Note
Snapshot reserve, if activated, can also cause disk space report discrepancies. For more information, see the Data Protection: Online Backup and Recovery guide.

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 might 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.

Getting accurate qtree space information

To get accurate space information about a qtree, complete the following step.

Step	Action
1	Use the filer `df` command instead of the client `df` command.