Help Me Understand/engineer A Backup Strategy.

I tried searching, but it appears the search is still broken.

Some of you know my other posts.. pleading for help with a problem (that's really sort of fixed itself/not remanifested itself).

Upon this whole ordeal I decided to re-evaluate my nonchelant backup strategy. Which currently is:

Backup our DB daily w/ transaction logs. (overwrite the backup daily on the tape).
Backup our DB weekly w/ transaction logs.

I rotate the tape weekly, on Monday morning. So there is a weekly backup and the last backup from monday morning on each tape.

Along with that I have some optimizations and shrinks I run.


Reading through the SQL BOL. It seems my strategy is ok, however if we lost the db at the end of the day, we'd lose a full days worth of work.

So. Here in lay the questions.

The BOL states to possibly back up twice a week, with differential daily backups and 4 hour transaction logs (example).

So, I sorta get that..

I make a device, "COMPANY.BAK", which writes to my external 'tape' unit.

I make a job to back up the complete DB on sunday. to "COMPANY.BAK". (Not sure if I tell it to truncate the transaction log?).
I make another job to make nightly differential backups to "COMPANY.BAK" with the 'append to media' switch on.
I make yet ANOTHER job to make a transaction log backup. Here's what I don't get. If I set this thing to run every 4 hours, since it's not a differential backup.. rather incremental.. doesn't it just overwrite itself each time? It doesn't append itself to the backup right? So how much data could be missing if the log is overwriting itself rather than appending to itself? Also, if I turn on truncate log on backup, aren't I missing possibly critical transactions from the log for a sucessful restore?

I guess I'm a bit befuddled here.