This is a techy post... my company almost lost a client over this issue, and it is confusing other clients of mine.
Summary: if your VXA drive suddenly quits working after a few weeks and no longer sees any tapes in the drive, try cleaning it before panicing.
On both UNIX and Windows systems, VXA backup will fail if you do not clean the drive every 72 operating hours. For a 4-hour backup, this is about every three weeks. If you do not clean the VXA tape drive with cleaning cartridge every 72 operating hours, the drive quits recognizing tapes inserted into it.
That's right: VXA tape drives will tell you media is not available if you do not clean the drive in a timely fashion. And the clearning light only comes on IF THERE IS NO TAPE IN THE DRIVE.
If you are accustomed to trouble-shooting, you probably would do what I did. First, I tried a different tape. Then I tried another backup program. Then I examined the backup log files, then the Event Viewer logs. There were no clues except that the drive saw no tapes.
On UNIX, I found nothing in the syslogs and tape status messages. I finally found the problem by digging into the Job Queue log in the Windows Removable Storage Manager. It indicated simply that "a cleaning is required before further tape operations can be performed."
Keep in mind that this is NEVER displayed to the user. It is NOT logged in Event Viewer, and it is not returned as a "tape needs cleaning" hardware error that UNIX recognizes. And since the cleaning light shuts off if there is already a tape in the drive, there's no good way for a user to tell that the drive REQUIRES cleaning.
Granted, their documentation says to clean the drive every 72 operating hours, but what user reads that? I would estimate that 25% of the users I instruct do 50% of what I tell them to do.
We use tape drives to back up data on client computers. As disk drive capacity has increased, tape drive capacity has needed to keep up. The Exabyte VXA-2 drive can back up 160 GB, but it has it's peculiarities. The only clue is a tech article from Exabyte or the Microsoft RSM log.
This is a post mostly for the sake of allowing other techs to find this in a Google Search.