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Delegations

A delegation is a token that the origin system grants the caching volume to ensure that the caching volume can serve read requests without the need for validating the data with the origin volume. Delegations are used only in certain situations.

When the FlexCache volume retrieves data from a file on the origin volume, the origin volume provides a delegation for that file to the FlexCache volume. The FlexCache volume retains the delegation until the origin volume revokes the delegation before the particular file gets modified. After the data is modified, the FlexCache volume must fetch the data before serving it to clients.

If multiple caching volumes have delegations for a particular file, then all the delegations are revoked before the file is updated.

Note: You can use the lock status -p flexcache command to view the FlexCache delegations granted by the storage system.

Delegations can cause a performance decrease for writes to the origin volume, depending on the number of FlexCache volumes that are holding delegations for the file being modified.

The following list outlines situations when delegations cannot be used to guarantee that an object has not changed: