Use at the server console to make a volume unavailable to users.
dismount volumename
Dismount allows you to maintain or repair a volume and to upgrade disk drivers while the NetWare server is up.
Use this command to dismount all volumes residing on a removable drive before you remove the drive.
If you are running out of memory and cannot add more RAM, consider dismounting a volume that is used infrequently.
Mounted volumes take up memory allocated for file caching and thus affect server performance. NSS volumes use much less memory than Traditional volumes.