The following figure depicts setting the subscription limit of pool capacity.
The subscription limit is the ratio (%) of the total V-VOL capacity that has been configured to the effective capacity of the pool. When the subscription limit is set, you cannot configure another V-VOL if the new V-VOL capacity would cause the subscription limit to be exceeded.
The subscription limit includes pages required to store user data and control information. The total capacity of V-VOLs that are created from the pool is smaller than the subscription limit capacity. The formula used to calculate the required pages for one V-VOL includes the control information. To determine the total pages required in a pool, multiply the number of calculated pages by the number of V-VOLs. The value enclosed in ceiling( ) must be rounded up to the nearest whole number.
Number of pages for the V-VOL including the control information:
Number-of-pages-for-the-V-VOL-including-the-control-information = ceiling((one-V-VOL-capacity (MB) + ceiling(one-V-VOL-capacity (MB) / 3,145,548 (MB)) * 4 (pages) * 42 (MB)) / 42 (MB))
For example, if the effective pool capacity is 100 GB and the subscription limit is 150%, you can configure up to a total of 150 GB of capacity to the V-VOLs related to the pool.
If the subscription limit is set to a value that exceeds 100%, or if the subscription limit is not set, you need to monitor the free capacity of the pool because a V-VOL larger than the effective pool capacity might be created.