Dell PowerVault TL2000 User Manual page 235

Note: When reducing the number of drives in your library, update the Logical
Library configuration. This will remove the Attention LED on the front
panel and the exclamation mark on the Home screen indicating that a drive
is missing.
Updating the Logical Library configuration will also update the drive element
addressing and drive numbering. Replacing LTO half height drives with full height
drives may require you to execute Restore Factory Defaults to correctly update the
drive element addressing and drive numbering. See "Configure Library:
Save/Restore Configuration" on page 5-56.
Appendix A. SCSI Element Types, SCSI Addresses, and Physical Configurations
A-7