TS1170 density code

I have a couple of TS1170 and a handful of TS1170 media to play with.
When defining the media type in CTA are the " primary density code" values still needed, and if so where can I find what the value is for the TS1170 media?



Hi Tim,

the primary density code is taken from the SCSI reference of the tape drives:

Have a look at the overview Table 7 — 3592 capacities by density, cartridges, and product on page 20 of the document (52 absolute page number).

At CERN, we have been using IBM TS1170 tape drives without primary density code (i.e. it is set to 0). I guess we forgot to set it. The correct value for IBM TS1170 is 59h = 89. I now corrected that in our production CTA environment.

I need to check where it is actually used and will get back to you on this one.

Best regards,


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Thanks! I’ve updated the entry this end too. Be good to know if it is actually used anywhere


Hi Tim,

we discussed this topic at the today’s CTA operations meeting.

As you may know, certain tape drives have a possibility to read and write previous generation media (= backwards compatibility).

Currently at CERN, we logically separate which tape drives can read/write which tapes (by using logical libraries concept). In the past we were considering the idea where CTA would automatically identify which tape can be mounted in which drive and use the highest available density.

Since then, the tape technology has changed, from what we expect now, the future drives will not support backwards compatibility (as is already the case with IBM TS1170). Instead, each new tape drive will only support it’s own dedicated media. This is not written in stone and can change in the future but as things stand now, IBM (the tape drive manufacturer) is not keen on providing backwards compatibility anymore (despite many smaller customers asking for it).

So, for the time being we are not planning to explore this automatic drive+tape matching concept, which means that the primary density code is not used anywere in operations.

I hope I clarified this point, let me know if you need more info. Best regards,


Thanks for the detailed reply Vladimir. feels right to have it there even if not used :slightly_smiling_face: