backups SQL

Hi

I want to have a full backup once per month and the a twice daily differential back up.So that I can go back to any half day point in the last 4 weeks

But do I get my full monthly backup to overwrite the existing full one in order to start again. and then does this mean that if i want to restore I can't go back 1 week because I have just done a full back up. (hope that makes sense)

e.g. I do a full monthly on the 30th which overwrites the existing media (incl all the diffs) then decide I want to go back to how the database was on the 22nd of the month...I can't because I've only got a full back up from the 30th)

Cheers

ICW

Why are you only doing a full backup once a month?

My standard practice is to do a full backup once a day, and backup the transaction log once an hour. (I've also got alerts set up to trigger a transaction log backup if the log exceeds 50% of its capacity.) I back up to disk, which creates files with the date and time of the backup, and then back those files to tape each night. I keep the disk backups on disk for 3 days, which allows me quick access to the backup in case of a problem. Beyond the 3 days it's relatively easy to recover the disk files from the appropriate tape, which is kept for 90 days. With this design I can recover any database to any time within the last 3 months.