Dean wrote, in part,  on 9/21/2004 4:12 AM:

>How about :
>
>Daily and Weekly kept for a month.
>Run a monthly backup that's kept for a year.
>If you need to, run a yearly backup that you keep for 7 years.
>
>This should use slightly fewer tapes than your current rotation.
>

Daily and weekly kept for a month ... thats about 30 copies at any point 
in time.

Monthly kept for a year ... that's about 12 copies at any point in time.

Yearly kept for 7 years ... that's about 7 copies. 

30+12+7 = 49 copies vs the current 180 (Exchange backup) copies.  That's 
using about 30% of today's total!

The number of tapes corresponds roughly to the number of images, at 
least for your full backups, so that's a nice savings, *IF* it meets 
your company's needs and expectations.

If you know more about your data, you can probably do better.  For 
example, maybe you could have one 6-week retention for everything, then 
a 7-year retention for a pair of full backups before and after year-end 
closing? 

"Best practice" is what fills your company's needs and expectations.   
cheers, wayne