Protected user-controllable volume snapshots

1. A method for a data storage system to allow a user on a host system coupled to the data storage system to update a snapshot in the data storage system, the user being without general editing privileges in the data storage system, the method comprising:

creating a read-write snapshot in the data storage system, the read-write snapshot being a copy of production data, the production data being in the data storage system;

exporting a logical unit number (LUN) assigned to the read-write snapshot to the host system;

providing the user with read and write access to the read-write snapshot but not write access to the production data;

receiving a request to update the read-write snapshot from the user;

determining from an access control list if the user is permitted to update the read-write snapshot;

when the user is permitted to update the read-write snapshot, updating the read-write snapshot by:

removing the LUN from the data storage system, comprising recording parameters of the LUN and deleting the LUN from the data storage system;

creating a new read-write snapshot that is another copy of the production data;

restoring the LUN for the new read-write snapshot, comprising

recreating the LUN from the recorded parameters and exporting the LUN to the host system, the recreated LUN and the deleted LUN having the same logical unit number; and

providing the user with read and write access to the new read-write snapshot but not write access to the production data.

2. The method of claim 1 , wherein:

when the user is permitted to update the snapshot:

prior to said removing the LUN, preparing the host system for removal of the LUN; and

after said recreating the LUN, preparing the host system for restoration of the LUN.

3. The method of claim 2 , wherein:

said preparing the host system for the removal of the LUN comprises instructing the host system to un-mount a file system of the data storage system from the host system; and

said preparing the host system for the restoration of the LUN comprises instructing the host system to mount the file system of the data storage system into the host system.

4. The method of claim 2 , further comprising:

said preparing the host system for the removal of the LUN comprises instructing the host system to halt a database in the host system from accessing the LUN; and

said preparing the host system for the restoration of the LUN comprises instructing the host system to resume the database.

5. The method of claim 1 , wherein the access control list comprises a user name and a snapshot name for the read-write snapshot that the user is permitted to update.

6. The method of claim 1 , wherein said creating a new read-write snapshot comprises creating the new read-write snapshot with a same name as the read-write snapshot.

7. The method of claim 1 , wherein said creating a new read-write snapshot comprises creating the new read-write snapshot with a different name than the read-write snapshot.

8. The method of claim 1 , further comprising:

receiving a request to edit the access control list from another user;

determining if the another user has administrative privileges in the data storage system; and

when the another user has administrative privileges in the data storage system, modifying the access control list according to the another user.

9. The method of claim 1 , wherein the user tests an application on the read-write and the new read-write snapshots.

10. The method of claim 1 , wherein the read-write snapshot is a virtual volume.

11. A method for a data storage system to allow a user on a host system coupled to the data storage system to update a snapshot in the data storage system, the user being without general editing privileges in the data storage system, the method comprising:

creating a read-only snapshot in the data storage system, the read-only snapshot being a copy of production data, the production data being in the data storage system;

creating a read-write snapshot in the data storage system from the read-only snapshot;

exporting a logical unit number (LUN) assigned to the read-write snapshot to the host system;

providing the user with read and write access to the read-write snapshot but not write access to the production data;

receiving a request to update the read-only snapshot and the read-write snapshot from the user;

determining from an access control list if the user is permitted to update the read-only snapshot;

when the user is permitted to update the read-only snapshot, updating the read-only snapshot with a new read-only snapshot of the production data;

determining from an access control list if the user is permitted to update the read-write snapshot;

when the user is permitted to update the read-write snapshot, updating the read-write snapshot by:

removing the LUN from the data storage system;

creating a new read-write snapshot from the new read-only snapshot;

restoring the LUN for the new read-write snapshot; and

providing the user with read and write access to the new read-write snapshot but not write access to the production data.

12. The method of claim 11 , wherein:

said removing the LUN comprises disabling the LUN on the data storage system; and

said restoring the LUN comprises enabling the LUN on the data storage system.