3 x LTO-1 Ultrium 230 drives (all reporting same error)?

[Richard Bickers]

Hi Rick,

The LTO drives write data to the tape in 'serpentine' format. I.e. forwards to the end then backwards to the start. Each of these (single direction) is referred to as a wrap and there are 48 wraps for a full volume in LTO 1.

There are two sets of heads - one for each direction. Each set has 8 write heads and 8 read heads (for read while write - that's where the capacity loss comes from).

The backup app is unaware of all of this. It treats all tape drives the same - a serial write of data from BOT (beginning of tape) until it reaches EOT (end of tape). Any mention of tracks, sections or whatever is independant of the actual tape format.

Having said all that.... it's possible for one set of heads to be in better shape than the other so the different directions could perform differently. The direction change would be based on the amount of data though. For LTO the wrap length is 2.25GB (after compression). You'd find every other 2.25GB goes at a different speed if this is the case.

I'm afraid you can't fix anything inside the box. They are very finely aligned during manufacture and all of the parameters are measured and constants set internally during the production process. What you've got looks to be aligned OK - just a bit dirty. My feeling is that if you can use new media (which is slightly more abrasive than old) and use the occasional clean then you might be able to improve things. Please don't poke around inside or you could upset the alignment.

Good luck,

Richard.

[Rick Kirk]

Richard,

Thanks for putting what I was trying to say into English :)

What you have describes is what I am seeing. Fast/Slow every 2.25 GB. I'll keep at it in the hope that the second set of heads clean themselves up also.

Thanks for the assistance. Much appreciated.

I'm getting 73GB per tape which is fine for my purposes.

Just running a verify process at present though I expect it will perform fine.

Regards,

Rick.