Amdump issues
If you have any problem with amdump first make sure that the command amcheck still succeeds. The amcheck command also points you to a much more detailed and to the point problem area than e.g. the amdump error "all disks failed". Here is list of issues that amdump may encounter:
Why does 'amdump' report `results missing'?
Why does 'amdump' report `disk offline'?
What if 'amdump' reports 'dumps way too big, must skip incremental dumps'?
What if 'amdump' reports `infofile update failed'?
Why does 'amdump' not dump to the holding disk?
Why does 'amdump' give me 'Tape I/O error'?
Why does 'amdump' report 'cannot overwrite active tape'?
'amdump' fails with error message '/sbin/dump returned 1'