What Snapshot disk consumption is
Data ONTAP preserves pointers to all the disk blocks currently in use at the time
the Snapshot copy is created. When a file is changed, the Snapshot copy still points to the disk blocks where the file existed before it was modified, and changes are written to new disk blocks.
- How Snapshot copies consume disk space
Data ONTAP preserves pointers to all the disk blocks currently in use at the time the Snapshot copy is created. When a file is changed, the Snapshot copy still points to the disk blocks where the file existed before it was modified, and changes are written to new disk blocks.
- How changing file content consumes disk space
The following illustration shows how Snapshot copies consume disk space before and after you change the contents of a file.
- Monitoring Snapshot disk consumption
The df command displays the amount of free space on a disk. It treats Snapshot copies as a partition different from the active file system.
- Displaying Snapshot disk consumption statistics
The snap list command shows the amount of disk space consumed by Snapshot copies in a specified volume. This command enables you to see how much disk space each Snapshot copy is using and helps you determine an appropriate Snapshot reserve. The snap list command also shows whether a Snapshot copy is currently being used for backup and whether it is needed for a restartable dump or another backup application.
- What the Snapshot reserve is
The Snapshot reserve specifies a set percentage of disk space for Snapshot copies. By default, the Snapshot reserve is 20 percent of disk space.
- Changing the Snapshot reserve
After you understand how Snapshot copies consume disk space and how the Snapshot reserve works, you can change the Snapshot reserve when needed.
