im using symantec exec 12 as backup software and lto3 tape drive 400gb capacity. my backup plan is daily full backup with rotation of tapes, but lately i always have this problem that when i comeback the next day to change tape, its asking me to put a new LTO3 tape and then continue to backup, and again ask for the first tape before finishing the backup. i cannot do this everyday as its requiring 2 tapes everyday. the one i cannot understand is that my LTO3 tapes is read as FULL with 800GB capacity. bytes written is only around 300GB. thats why it will ask for second tape. please advice fellows.
If you backup server cannot acquire the data from the network fast enough, you're left with slack space all over your tape. This can add up to a significant loss of space on the tape.
Investigate the throughput you're getting and whether there are any bottlenecks you can resolve.
Also ensure that you have selected hardware compression on the job. The LTO3 tapes are 400Gb raw but are listed as 800Gb under ideal scenarios with compression. Depending on the data you're putting on the tape, you might get a compression ratio better than or significantly worse than 2:1
If you're struggling to get sufficient throughput from your client servers, you can look at shutting down some services during the backup period. For example, most file servers will back up far faster if the antivirus on-access scanner is disabled during backup. In my environment, use the pre & post commands in backup exec to send 'net stop avservice' and 'net start avservice' before/after a backupjob. You can do likewise to shut down other services depending on the server type. For example, a lotus domino server can be backed up much faster if you stop the LotusDominoServer service... this is often acceptable if a backup runs overnight.
Another alternative if you have the resources is to stage your backups to a backup-to-disk volume, then later stage it off to the tapes.