| ERROR | active use of diskgroup string precludes its dismount |
| CAUSE | An ALTER DISKGROUP ... DISMOUNT command specified a diskgroup which had database client instances with open files in the diskgroup. Diskgroups cannot be dismounted until all open files in the diskgroup are closed by the database client instances. |
| ACTION | Stop all clients that are using this diskgroup and retry the ALTER DISKGROUP ... DISMOUNT command. The V$ASM_CLIENT fixed view in an ASM instance provides a list of its active database client instances. |