LTT Environment data

[David C Partridge]

For some LTO tapes in a batch I just bought (used), I'm getting a warning message when I run an LTO Media Assessment Full Tape Test that says:

Maximum temperature limit has previously been exceeded

When I click the health button and look at the Cartridge Environment section it says:

Maximum temperature margin in last 3 drives: Great Margin
[] Minimum temperature margin in last 3 drives: Warning, below minimum (-200%)

I'm seeing these two for all cartridges I've tested in this batch even though only some issue the Maximum temperature limit message.

So, 

1 How should I interpret what LTT is telling me here?  and

2 Should I be concerned about using these cartridges? (Other than this and a Data on tape (average) warning, all seem to pass tests with "Great Margin".

Thanks, Dave

[Curtis_Ballard]

In short - YES, you should be very concerned about using tapes that report a maximum temperature warning.

That warning is only generated when the drive measures a temperature at which permanent media damage is likely to occur.  It is a latched warning and is written to the tape since the damage is permanent. 

You also mention a "Data on tape average warning", that normally means that tape damage has occured.  If you get a combination of that message and a maximum temperature then you don't want to use those tapes.  They almost certainly have physical damage from over temperature and even regions that are still able to be written may fail suddenly.  If there are other tapes in a batch that don't report the maximum temperature but report a data on tape average warning those other tapes were probably also damaged by high temperature but were not loaded in a drive at the time.  The warning is only able to be written to the tape if the tape is loaded in a drive when the over-temperature event occurs.

[David C Partridge]

Thanks for the clear explanation - I suspected as much.

Dave