I upgraded our installation to 7.6.1.3, but this did not resolve the issue.

Next I noticed that the daemon log was having entries complaining about not 
being able to set the tape device block size to 128 kB because the hardware 
only supports 64 kB. Good enough, I went to the NMC to check the configured 
block sizes for both tape drives.

The BS values for both drives were set to something called "handler default", 
I changed them to 64 kB and hooray - all was good again. I can use all my 
tapes and backup jobs run just fine. I have a case open with EMC support but 
they did not figure this out, it seems that something has changed with 7.6 SP1 
requiring this change since I have not touched this value before.

-Kimmo

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