Best Backup Plan ?

you will get about as many opinions of what is "best" as people who respond.

Here is my thought(s) and the reasons why...

Lets assume you buy into the idea that a new drive has a 50% chance of failure in 3 years.
the math on that is about the same as 50% chance of failure in 1000 days
or about the same risk as a 1 in 1000 chance taken every day for 1000 days.

in otherwords every day your turn your pc there is a 1 in 1000 chance today is the day its going to die.

the same 1 in 1000 chance is also true for your backup.
you have a 1 in 1000 chance that when you turn to your backup to save your ass it will fail you.

if you multiplex your backups onto two different devices such as a usb drive and a network drive.
then chance of both letting you down in the same day is the risk squared
or (1/1000) * (1/1000) = 1 in a million.
so simply multiplexing your backup doubles your storage but reduces your risk from 1/1000 to 1 in a million.

Its for the above mathamtical reason that the single biggest bang for the buck is to multiplex the backup.

For critical data I multiplex my current backups and use chain2gen to keep multipe generations (gfs) backups.

A typical configuration for me is:
linea does a full on 1st_sun with daily incr all going to a network drive with 2 generations
lineb does a full on 3rd_sun with daily incr all going to a usb drive

what this means is no mater what day of the year my critical data crashes
to restore my system to a current backup I have a 999999/1000000 chance of success.

depending on how may generations I keep on linea and lineb I can go back 45 days or more
and each of those 45 days will be at 999/1000 assurance or 999999/1000000 assurance.

chain2gen is here:
http://forum.acronis.com/forum/5940

I'm still testing but in my opinion the best backup strategy is the following:

I have two depots which represents two directories on a machine in the network.

Each sunday morning a full backup to depot 'internal backup'. Each workday morning at 00:05 am and over lunchtime a differential backup. I use differential backups because for a restore only two backups are needed. So the performance seems to be better.
Each saturday at 00:05 am I make a full backup to depot 'external backup'.

In addition I weekly make a copy of the 'external backup' depot to deposit it in the safe of my bank. For the 'external backups' I have three external USB harddisks which I rotate weekly. The USB harddisk I will configure so, that after connecting to the machine hosting the depots an automatic copy of the TIB-Files will started.