Running out of tape when half full???

[Matthew Claridge]

Hi,

Hope someone can shed some light on this. Suddenly my backups have 
started failing due to the tape running out of space:

*** A TAPE ERROR OCCURRED: [[writing file: No space left on device]].
FAILURE AND STRANGE DUMP SUMMARY:
 server1.rwa /var lev 0 STRANGE
 server1.rwa /usr/local lev 0 FAILED [out of tape]
 server1.rwa /usr/local lev 0 FAILED ["data write: Connection reset by peer"]
 server1.rwa /usr/local lev 0 FAILED [dump to tape failed]

NOTES:
 taper: tape DailySet202 kb 34175264 fm 16 writing file: No space left on device


However, I'm using an 80GB (uncompressed) VXA tape:

tapetype VXA2-V23       # what kind of tape it is (see tapetypes below)

define tapetype VXA2-V23 {
   comment "Exabyte VXA2 tape drive and V23 tapes"
   length 76209 mbytes
   filemark 3908 kbytes
   speed 3956 kps
}

Anyone have any ideas as to what's going on?

Thanks in advance,
Matt