LTO cleaning

There are so called built-in indicators - how they operate exactly is unknown to me - not sure if there is internal mechanism which detects "dirt" on heads by measuring its "shape" and "weight" at micro level (that would be expensive) or does use special algorithm based on usage and then does guess when it needs to call for cleaning... I know that write/read errors in the past (and not too I guess) used to automatically call for cleaning - not sure if that was due to NW or drive code - I guess such errors could be interpreted as head contamination too and trigger cleaning by drive too. Their behavior will depend on drivecode (firmware) in certain circumstances.

The information is passed to NW via tape alert mechanism (same applies to other backup applications).

I know the read/write errors that called for cleaning were generated by the drives. I know from past experience that read/write errors will call for a cleaning at the drive level. Also most drives will call for a cleaning after a certain interval, usually based on hours of use, at least that is what I have experienced.

There seems to be quite a few theories on how this works! Initially when LTO first came out I was told that the drives did not need cleaning and what was happening during a clean was actually a recalibration by running a fixed length of tape by the head. However I am reasonably sure this is not necessarily correct.

I have also been told that the cleaning tape is abrasive and multiple tape cleans will cause the heads to wear down.

Another bit of information I have heard is that the need for cleaning is detected by the pressure the head exerts on the tape as it goes by - again I am not certain of the truth in this as I was of the understanding that LTO heads were non-contact!

Last bit of information I have heard is that the LTO tape itself has a cleaning agent within it that has some part in keeping the heads clean. Again if LTO is not-contact then this does not seem correct!

I'm not sure if LTO standards define how cleaning should be done or if this is left to vendor itself... but I remember early days and those statements that cleaning was not required. Things went so far at one moment that official claim was LTO didn't need cleaning while they did existed and HW support did have it, but they were not available on market. I would speculate that early plan was that LTO could provide technology where cleaning would not be required (something like dust-cleaning mechanism we see in modern dSLR cameras where there would be a micro shake of head "cleaning" the dirt of the head). Obviously that didn't work and cleaning tapes were reintroduced.