Re: [lopsa-tech] tapes getting old?

[Andrew Hume]

well, i've never had LTO-3 tapes, but i've written a few thousand LTO-2 and LTO-4s. without more details, i would venture that the drive is not working correctly. we just had a drive behaving oddly (premature EOT) and had a guy from Fujitsu come out to look at the media. he had a whizzy little machine that read a flash memory inside teh tape cartridge that recorded the last few times the tape did I/O and so forth and how the drive did. it took about 10s per tape and i got a neat little report on the spot (this verified my problem of tapes reporting premature EOF -- i normally get 860GB+). the tapes indicate that the tape drives were doing massive numbers of retries, and this sucked up the capacity. i would just have the drive serviced, especially if you want to trust the results. (you do verify the written tape on another drive, right?) andrew

AT&T Capacity Analysis.pdf
Description: Adobe PDF document

On Mar 4, 2011, at 10:50 PM, Edward Ned Harvey wrote: I have an LTO3 tape autoloader.  It's been in production for about 3-4 years, but it's never been reliable.  For the last 9 months or so, it's been so unreliable I've barely used it at all, but now I'm working hard to bring it back to life.   Right now, I have a very repeatable behavior:  I can write all the data I want to all the tapes I want, as long as I only write zero's.  But when I write any real data (containing a mixture of 1's in it) then I can only write a small amount of data (1M or 100M or so) it varies...  And it exits with IO error.   Tapes have been in rotation.  Meaning we don't just write once and archive permanently.  We write them, take them offsite, and some time later they will eventually rotate back in to be written again.  I don't know how many times each tape has been written ... I would guess 5 times each roughly.   I wonder, maybe the failure mode for LTO3 tapes is that they start becoming unwritable when they're old?  Or unwritable when they've been written more than X times?   Any ideas?  I tried googling, but didn't find anything relevant.   Thanks...   _______________________________________________ Tech mailing list Tech@lists.lopsa.org https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/ ------------------ Andrew Hume  (best -> Telework) +1 623-551-2845 and...@research.att.com  (Work) +1 973-236-2014 AT&T Labs - Research; member of USENIX and LOPSA

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