>I support a 24x7 research facility, so the start windows are driven by
our >operational schedule. 

As they should be.

>8:00 am Tuesday to 8:00 am Wednesday is a maintenance period, so I run
full >backups then to minimize impact on system performacne during
operations.

And looking at your previous post, you're doing incrementals 6pm to 6am.

>Currently, a full backup can take up to 48 hours to complete 

Ah HAH!  Design rule #2, no matter what I have to do, all backups must
complete each night/day.  That may sound like stating the obvious, but
so many of my other design principles come from this assumption.  I
think your problem is being caused by trying to do everything in one
night.  (Design rule #1 is that tape drive must be streamed.)

Have you ever considered spreading your fulls out across the month?
Switch to a monthly full backup, weekly cumulative incremental backup,
and daily incremental.  That way, you only have to do a full backup of
1/28th of your environment, a weekly cumulative of 1/7th of your
environment, and an incremental of the rest.  This is kind of my
standard schedule layout.

>(more drives on order ;) ) 

I'm willing to bet that you don't need all (if any) of those new drives
to accomplish what you want to do.  You just need to reconfigure your
backups to properly use the ones you have.  And, of course, there are
companies that can do that for you... <cough, cough>

>Is it necessary for the start windows to match exactly, or is it enough
for >the start time of the window to be the same?  

I _think_ you can get by with the start time being the same, as long as
the one with the less often frequency has the longer window.  But I
think the secret is in my suggestion above.

---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies

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