The snap list output is calculated in a number of ways. The output can show both used space and available space.
Cumulative Snapshot copy space is the total space used by this Snapshot copy and all other recent Snapshot copies (the ones preceding this Snapshot copy in the snap list output).
Summary of the snap list command output: The %/used number is useful for planning the Snapshot copy reserve because it is more likely to remain constant as the file system fills.
The information shows a volume that keeps five nightly Snapshot copies and four hourly Snapshot copies.
The sample output shows that the overhead for Snapshot copies is only 10 percent, so the default Snapshot copy reserve of 20 percent seems to be a waste of disk space. If this pattern of change holds, a reserve of 12 percent to 15 percent provides a safe margin to ensure that deleting files frees disk space when the active file system is full.
The values in parentheses, which show the space used by an individual Snapshot copy, are useful in identifying a particular Snapshot copy to delete when the file system is full. However, deleting a particular Snapshot copy does not necessarily release the amount of disk space indicated because other Snapshot copies might be referring to the same blocks.