A client has two external USB hard drives which are being used to store backups. The idea is to have hard drive 1 perform incrementals on a Mon, Tue, Wed and Thur, it will then do a Full backup on a Friday and then be replaced with the second drive which will follow the same pattern, being replaced after Friday's full backup with drive 1 and starting the cycle again.
We've got the Friday night full backups in place, but I'm not sure about the incrementals. Using ntbackup, do I need to have 4 backup jobs for Mon, Tues, Wed and Thur so that the files rotate, or can I simply have one file and replace it? What I'm confused about is what is backed up in an incremental, everything modified since the last full backup or everything modified since the last incremental. If it's the latter, then obviously I will need 4 jobs, if it is backing up everything since the last full backup then I can have just 1 job which will replace the file from the previous evening.
I know rotating drives on a weekly basis isn't a brilliant method, but the client won't be looking into daily rotation and tape drives imminently. (They have a rather small network at present, and actually data wise they save and modify very few files)