Setup: 20 tapes (VXA-2 v-23) Native capacity 67GB. 1 dump cycle. Amanda version 2.4.2p2 Holding disk 105GB All DLE are Samba shares for Win95/98/NT6/Win2000.
Problem:
I am now 7 tapes into the second rotation and the level 0 backups are being overwritten. It seems to be due to the large size of incrementals being archived on a daily basis. There are numerous days where Amanda only does incremental (level 1) and even so Amanda is not able to fit them all onto the daily tape.
So you have a dumpcycle of 28 days (assuming you run only on weekdays) and a runspersycle of 20. One of the disadvantages of a large dumpcycle is that the incrementals take up so much space; and having only level 1 incrementals of smbclient makes this even worse, as you can see.
I can't garuantee it works much better, but giving the large holdingdisk you have, I would give this setup a try:
tapecycle 20 tapes dumpcycle 14 days runspercycle 10 runtapes 2 inparallel 10 dumporder "TTTTTTTTTT" # or S's taperalgo largestfit
This will dump up to 67*2=134 Gbytes each day. Once tape is filled during the backup, leaving up to 67 Gbyte in your holdingdisk to be flushed on the next tape each morning. The dumporder and taperalgo parameter help to fill the first tape up to the last byte.
If you have any money left, I would add a second set of 20 tapes too.
Paul