Vista - Backup Files Space Problem

I schedule an automatic “Backup Files” for everyday at 1 AM. The initial backup takes 125GB of space, and then each day incremental backups take small amounts of space. Every sixth or seventh day the automatic “Backup Files” program does another complete file backup instead of an incremental. This backup takes up another 125GB of space. In a months time I have no space left on a 500GB backup drive and then have to delete the set and start over again.
Why does the backup program revert to backing up all the files every 6 to 7 days? Is there a setting that can be adjusted?
Regards, Gary

The algorithm they use to decide about full vs. incremental backups can be
found here:

http://cfsbloggers.members.winisp.ne...crementall.jpg

A new, complete file backup will result in creating another Backup Set; when
that happens, I simply delete the previous Backup Set. I could wish that
Vista had an option to automatically delete that previous Backup Set, but
none that I have found.

"allgevista64" <allgevista64.34kq91@xxxxxx-mx.forums.net> wrote in message
news:allgevista64.34kq91@xxxxxx-mx.forums.net...

John,

Thanks for the information.

The difference in what you explained is that when there is another full backup, automatically created, it is not done in another Backup Set but simply added to the existing set. This means that, regardless of the size of my backup disk, it will eventually fill up and I will manually delete the one Backup Set that has multiple full backups in it and begin again. This seems impractical if I understand it correctly.

You wrote that you delete the previous Backup Set. How do you configure the program to create multiple Backup Sets versus simply adding full backups to the one original Backup Set?

Regards, Gary

Gary -- It has been some time since I last deleted a Backup Set. My current
Backup Set dates from December 6th, and I have it set for weekly backups, so
am on my 13th incremental backup since that time. Not sure this will be
helpful, but my Backup File folders have these sizes within my current
Backup Set:

Folder Backup Files date
Size, MB
---------- -------------------
46,512 12/6/2007
179 12/9/2007 9:04
621 12/16/2007 9:04
22,238 12/23/2007 9:34
81 12/23/2007 11:44
228 12/30/2007 9:04
7,762 1/6/2008 9:03
4,258 1/13/2008 16:53
122 1/13/2008 18:33
14,935 1/20/2008 9:12
283 1/27/2008 9:41
3,941 2/2/2008 11:04
1,100 2/9/2008 11:00

I still have 46 GB available on my nominal 160 GB external hard drive. I
realize this does not answer your question, but just now I do not remember
exactly how my current Backup Set was created; but my recollection is that a
new Backup Set is created when a 'full backup is done'.

I also have the following 'notion' although not sure it is well founded:
When I first began doing these automatic backups, it seemed that the
incremental backups were quite large, often almost as large as the
'complete' backups. I have read that any little change to a file or folder
will cause it to get listed for incremental backing up again, and that
antivirus programs were a main cause of small changes being made. Since I
changed my antivirus program in December from Norton to Avast, my
incremental backups seem smaller and that perhaps Avast is not messing with
my files as much as Norton did. That is about as scientific as a wild
guess, but I do seem to experience smaller incrementals than I used to.

See:

http://blogs.technet.com/filecab/arc...-expected.aspx



"allgevista64" <allgevista64.34mbw3@xxxxxx-mx.forums.net> wrote in message
news:allgevista64.34mbw3@xxxxxx-mx.forums.net...

John,
This does explain the experience of large incremental backups. In my case an incremental can be as large as the original every 6 or 7 days. I am using a McAfee virus scan program. I think it might be easier to look for a backup program that works with Windows Vista 64bit. Thanks for your time and expertise.
Regards, Gary