Monitoring used pool capacity and used pool capacity reserved for writing

• Monitoring used pool capacity

The used pool capacity must always be monitored. As data is written to DP-VOLs and stored in the pool, in cases where DP-VOLs are over-provisioned, the pool might become full before the DP-VOLs become full. Therefore, the used pool capacity must always be monitored to preven this from happening. A threshold value is set for the used pool capacity. If the used pool capacity exceeds the threshold value, a SIM is reported and a notification is sent to the hosts. If these SIMs are reported, you can resolve the status of the threshold exceeded by expanding the pool capacity or by deleting data. See Thresholds.

• Monitoring used pool capacity reserved for writing

For the pool consisting of pool volumes carved from an accelerated compression-enabled parity group, you must monitor both the pool used capacity and the pool capacity reserved for writing. If the used capacity exceeds the threshold value, a SIM is reported. The pool used capacity and the pool capacity reserved for writing are not always the same, and the SIMs are independent of each other. The following are conditions that can occur:

• The used pool capacity exceeds the threshold, but the pool used capacity reserved for writing is lower than the threshold.

• The used pool capacity is lower than the threshold, but the used capacity reserved for writing exceeds the threshold.

• Both used capacities exceed the threshold.

If SIMs are reported, you can resolve the status of threshold exceeded by expanding the pool capacity or deleting unwanted data.

If pool volumes that are created from an accelerated compression-enabled parity group are used to create a new pool, you must estimate the data savings percentage beforehand.

For a pool with a pool volume that has accelerated compression enabled, the used pool capacity and the used capacity of the capacity reserved for writing are monitored. The following shows the threshold values for the used pool capacity and the used capacity reserved for writing, which trigger output of SIMs when exceeded:

• Warning Threshold: You can set a value in the range from 1% to 100% in 1% increments. The initial value is 70%.

• Depletion Threshold: You can set a value in the range from 1% to 100% in 1% increments. The initial value is 80%.

• Prefixed Depletion Threshold: The value is set for the used capacity of the parity group. The value is fixed at 90%.

The figure below shows the pools used capacity and pools used capacity reserved for writing with threshold values. The smaller free capacity between the pool or drive is called the remaining free capacity for which writing is assured.