Gents,
I have the same problem. Tandberg Storage Loader 7818-LTO (LTO6), SAS interface (with ATTO ExpressSAS Card ESAS-H680), directly attached to the Dell (via SAS cable) DL2200 running BE 2010 R3. Tandberg troubleshooting utilities run fine - tape mounts, writes, erases fine. I ran a "duplicate to tape" job and wrote over 1tb of data to the tape without issue. Tape device shows online after the job completes, but when I run a subsequent job, the tape drive goes off-line and will not stay online until I restart the BE services and restart the job. This is a new Storageloader, so I have no reason to suspect the tape drive. I have a 3535-LTO at another site that I can try (to see if I get the same problem), but I don't have it with me today. I have had the DL2200 for a year and a half, but this is the first time I have a tape drive attached to it. Any ideas?
I should add that I'm running Windows Server 2008 R2.
I should also add that when I check the windows event log, I see 58053 errors ("the drive hardware is offline"). I also see a fair number of APNMCP "Information" (Event ID 0) events as well, but I don't think they're related to this problem. Other than this, the event log is pretty clean.