On Apr 5, 2009, at 8:44 AM, admbackup wrote:

Well it is a daily backup and it has been worked correctly since
two weeks ago.  And all the paths and the drives of the library are
online

Then you have a clear-cut case of something having changed, which
facilitates your pursuit.  Find the point when it last operated
correctly and from there look forward in your Activity Log for issues
with the mount point shown in 'Query SEssion Format=Detailed', which
is your key information for uncovering what the problem is.  Also
employ the 'SHow LIBRary' command to report the status of the
library, to possibly reveal additional issues.  You don't indicate
any problem with other client use of that TSM server, so see if
ordinary Backup/Client activity can make use of the same device class
and drives.  If not, go to the operating system level on the involved
TSM server and see if you can get a tape to mount via OS command (for
example, mtlib, or whatever library command is appropriate to your
hardware type).  Assure that the library device driver hasn't
changed, which could prevent proper communication with the library.
Look in your OS error log for indications of problems.  Physically
inspect the drives and library to assure that all is in fully
operational order.  If a SCSI type library, check the Elements
addresses to assure that nothing went wrong.  If there was an OS
restart, the order of addressing just might have changed.  (You have
all the details there; we have none.)

   Richard Sims