> Are you backing up already compressed files ?
No.
> Are there any soft/ hard read or write errors on the
> tape ?
I have examined every tape statistics and all backuplogs.
Here are all the tapes, with errors and failed or successful backups in the last few weeks:
Tuesday 278.583 Soft write errors. 6 backups failed.
Wednesday 21.222 Soft write errors, 13 Soft read errors, 2 backups failed.
Thursday 611 Soft write errors, 72 Soft read errors, 2 backups successful.
Friday 567 Soft write errors, 102 Soft read errors, 3 backups successful.
Week1 309 Soft write errors, 1 backup successful.
Week2 17.884 Soft write errors, 110 Soft read errors, 1 backup failed, 1 backup successful.
Month1 12.091 Soft write errors, 1 backup successful.
Month2 29.698 Soft write errors, 1 backup successful.
Month3 97 Soft write errors, 25 Soft read errors.
What conclusions can I make of that?
> Does the backup need to span to another tape ?
No. Never has.