I am noticing that sometimes the Avamar backup job logs an exception for volumes that are excluded from backups. For example, by default we have the A:\ volume excluded from all backups, yet I occasionally receive exception notifications with the following error in the log:

2014-02-17 01:16:43 avtar Error <0000>: Unable to retrieve volume information for 'A:\' (Code: 0x57 code 87: The parameter is incorrect)

Why does this error occur, and should it even be appearing for volumes that we've excluded?