12-09-2011 07:17 PM
I wish Ghost could do differential backups too. Especially when doing Cold Backups.
There is another popular program that can and it's a very nice feature. Being able to do that on an unscheduled basis would also alleviate the problems we see here about not being able to "reconcile changes" because it would be comparing the actual existing image to the current system and not relying on any kind of bitmap of the drive to track changes.
12-10-2011 02:41 PM
Thanks very much for taking the time to make sure I'm straightened out on this. :)
I think I will be fine with a base backup on the first day of the month and incremental backups every Saturday. I plan to have 6 recovery sets in this backup job so I should have 6 months worth of backup information on my external hard drive.
Reading all the replies has generated more questions....would you mind answering?
At the end of 6 months/recovery points, what happens? Does the backup job "end"?
If I need room on the external hard drive, can I just delete the oldest recovery point/backup set? Or, better question, if I have to delete a backup to make room on the external hard drive, which should I delete?
Is an incremental backup any good without its base?
Where are you guys finding the size of your incremental backups? Is it important to know? Is your concern that if they are large or taking time to run that you would do incremental backups more frequently? Or is it more a concern of the reliability of the incremental backups when they get too large?
What is the difference between an incremental vs differential backup?
THANKS SO MUCH for helping me learn this stuff!!!
12-10-2011 03:03 PM
Your backups will continue after 6 months providing you have not run out of room. Ghost will make the 7'th base image and then delete the oldest backup set. So you will always have 6 sets, 5 will be complete sets and the 6'th will be the current set in the making.
We are just looking at the incremental files in windows explorer to see the sizes of them. As mentioned it depends on how much your system changes in between the backups. In some situations it may cause people to rethink the backup schedule, especially if you were doing them every day.
Ghost only does incremental backups. Incremental backups are all dependant upon each other. Although Ghost makes it seemless to the user, it really is putting together all the incremental files in the set. Think of it as a chain that cannot be broken, each new incremental is based upon the changes compared to the last incremental.
A "differential" image would be comparing the changes to the base image instead of the last incremental.
So it would only need 2 files for the restore, the base image and the differential instead of the whole chain of incrementals.
For ongoing backups, in most cases "experts" think that incrementals are more efficient and result in smaller files.
However, since all systems are used differently that is not always the case. One advantage of differentials is that you don't need to keep them all, even if they were to take a little longer to make they would be a more efficient use of space.
We have been asking for a while to have a choice, maybe someday Symantec will give us the option.