backup/amflush oddity

[Jeff Portwine]

Hi everybody,   Hoping somebody can clarify something about amanda for me.   I have my backups set to run on a 3 day dump cycle with 6 tapes, running every evening except sunday night.    It seems to work fine, we change the tape each morning so over the course of a week (if I understand how amanda works right) we get two sets of full backups.    Sometimes we forget to change a tape, and most Saturdays we don't have anybody here to change the tape so on those days I thought that Amanda just backed up to the holding disk and then the next morning we could just change the tape, do an amflush, then change the tape again so that it would be ready for the next night.    However, I've noticed that every time Amanda doesn't find a writeable tape (usually due to the tape not being changed that day) there is very little data written to the holding disk and the amflush is very very small.   The day after this, the dump is much larger than usual compensating for this.    When we change the tapes every day,  each tape is usually around 50% full.    On a day when we forget to change the tape or are unable to change the tape the amflush results in about 0.5% tape useage, and the day following the day we did the amflush tape useage is usually 85-90%.      Is this how it's supposed to behave?   How can I fix it to do a normal dump to the holding disk on days when either we can't change the tape or we forget to change the tape?   Thanks for any explanation and/or tips.   -Jeff