LTO Tape drives after extended use will request cleaning with an error code of "C" on your drive's front panel LED. We recommend IBM, Fujifilm or Quantum brand cleaning cartridges. Avoid grey market sellers can sell you very old cleaning cartridges that're not compatible with newer LTO tape drives.
Please DO NOT routinely use a cleaning cartridge under the assumption that you're performing regular maintenance. Each time you use a cleaning cartridge it degrades the read/write head, think of the process similar to sharpening a pencil.
Only insert a cleaning cartridge when the tape drive requests to be cleaned, and if you've cleaned the drive and the light is still ON, please STOP using the drive and submit a support ticket for service.
In some cases a cleaning light can be triggered by inserting a dirty or bad data cartridge. It is a good idea to always try a different data cartridge if you're having cleaning light issues often, as you should rarely need to clean your LTO tape drive.
Here are some cleaning cartridge part numbers:
Quantum - MR-LUCQN-01
IBM - 35L2086
Fujifilm - 600004292