It's full when TSM reaches the End of Tape (EOT) mark. At that point, it knows exactly how much data it put on the tape.
It shows a percentage utilized as less than 100% when data has been expired on that tape. By default, when a primary tape pool percent utilized reaches 60% (the reclaim percentage) that tape becomes eligible for reclamation. At that time all the valid data on that tape will be moved to other tapes and returned to scratch. The way it determines estimated capacity is interested. In the case of LTO2, it will show an estimate capacity of 200,000MB (that's the native uncompressed capacity of the tape) until it writes more data than 200,000MB. From then on, it reports estimated capacity equal to the amount of data actually on the tape. It ahs to do this as there is no way to know how much data can actually be written (when compression is used). The only time you really know how much data can be written (when estimated capacity = actual capacity) is when the tape is full. So it is not unusual to see tapes with widely varying capacities. Another interesting fact that you might notice is an estimated capacity of the storage pool. That's computed by taking an average of the full tapes and multiplying by maxscratch. Just a useless bit of trivia to add to your brain. Thanks, Kelly J. Lipp VP Manufacturing & CTO STORServer, Inc. 485-B Elkton Drive Colorado Springs, CO 80907 719-266-8777 [EMAIL PROTECTED] -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Angus Macdonald Sent: Thursday, April 19, 2007 3:52 AM To: ADSM-L@VM.MARIST.EDU Subject: [ADSM-L] How are tapes declared full Doing some maintenance, I notice that most of my LTO2 storage pool tapes are designated as full, although their % utilised is sometimes less that 60%. The estimated capacities also vary from 320GB to over 600GB. I'm not actually having any problems but how does TSM decide the estimated capacity of a tape and whether or not it is full?