HP Storage Essentials V5.1 User Guide Second Edition (Linux Release) (T4283-96056, November 2006)

Finding an Element’s Storage Capacity588
NOTE: If there is not enough data to display, Capacity Manager does not display the chart. For
example, if you selected the weekly option from Frequency drop-down menu and you only have
two days of data, a chart is not displayed regardless of the value in the Trend field. Capacity
Manager does not display a chart if there is not enough data and the trending number is ignored.
Different Results for the df -k Command and Capacity Manager
If you run the df -k command on UNIX for a storage system, you may notice the total capacity
displayed does not match the total capacity in Capacity Manager. This difference occurs because
Capacity Manager calculates the total capacity differently than the df -k command. The df -k
command calculates the total capacity as follows:
used capacity + available capacity + reserved capacity
Capacity Manager calculates the capacity differently, as shown below:
used capacity + available capacity
The difference between the two calculations is the capacity reserved for superuser. If a file system
has a reserved capacity, the total capacity from the df -k command and Capacity Manager will
differ.
For example, assume you ran the df -k command for the file system, /dev/dsk/c0t0d0s0. After
you run the df -k command, you notice that the total capacity displayed is 6688076 KB. When you
look at Capacity Manager, the total capacity displayed is 6621196 KB. Actually, Capacity
Manager displays results in megabytes, but for this example, it is easier to have the totals using the
same units.
The totals differ. How did this happen? When you ran the df -k command, the computer ran the
equation mentioned earlier (used capacity + available capacity + reserved capacity):
1904031 KB + 4717165 KB + 66880 KB = 6688076 KB
where
• 1904031 KB is the used capacity
• 4717165 KB is the available capacity
• 66880 KB is the capacity reserved for the superuser. The percentage of the reserved capacity
can be set when using the newfs -m command.
Capacity Manager calculated the total capacity by using the equation discussed previously (
used
capacity + available capacity
) and displayed the result in megabytes:
1904031 KB + 4717165 KB = 6621196 KB
where
• 1904031 KB is the used capacity
• 4717165 KB is the available capacity
Because Capacity Manager does not include the reserved capacity in its calculations, the difference
between the two calculations is the capacity reserved for the superuser, which is 66880 KB.