Incremental vs Differential

[TomAZ]

When using an imaging program, do you prefer incremental or differential backups -- and why?

[TheRollbackFrog]

Basically, any file content flaw in any incremental will wipe out the whole backup as far as restoration is concerned while a differential will stand on its own. Although the incrementals are small, the differential will grow over time.

I use only differentials and when they become 50% of the size of a FULL backup, I re-do the FULL and start over.

[moontan]

i like the concept of differential better but my images are small enough that i never had to use either of them.

[Raza0007]

I used to use Differentials but then switched to incrementals. If you are using incrementals you need a reliable software to make them, like Macrium or Shadowprotect, because with incrementals if one link in the chain is corrupt, the whole chain fails.

Differentials do not suffer from this problem but since they are individually liked with the first base image, their size grows alarmingly.

Incrementals are very fast to create. Differentials take considerably more time to create as compared to incrementals.

[MarcP]

I prefer differential. I have a script running every day that deletes any differentials older than 14 days so space usage is kept low. Because of the way differential backups works, it's possible to delete older images without impact. Can't do that with incrementals.

As previously mentioned, you just need one bad incremental to mess up the whole thing.

[TomAZ]

Originally Posted by MarcP

I prefer differential. I have a script running every day that deletes any differentials older than 14 days so space usage is kept low. whole thing.

What image software are you using? How often do you run a new Full image?

[MarcP]

I use Macrium Pro. I run a full backup on the 1st of every months, but keep the previous month's backup and it's last 14 days of differentials until the 14th of the new month. So basically I always have a full month of backups done to a 1TB drive. Never ran out of space.

[MarcP]

Originally Posted by Raza0007

Differentials do not suffer from this problem but since they are individually liked with the first base image, their size grows alarmingly.

If you constantly add new files to your HD, I can see that. But you delete files and create new files often. Disk space used one day of often used by something else or no longer used at all. So differentials aren't always increasing in size. I have many that actually shrink because my usage fluctuates every day.

If you modify large files, only the modified blocks are backed up, not the whole file.

Size doesn't grow alarmingly at all and it takes less than 20mins to make a differential. My computer turns on automatically at 5:30am to take the backup so I never feel it.

[Raza0007]

Originally Posted by MarcP

If you constantly add new files to your HD, I can see that. But you delete files and create new files often. Disk space used one day of often used by something else or no longer used at all. So differentials aren't always increasing in size. I have many that actually shrink because my usage fluctuates every day.

If you modify large files, only the modified blocks are backed up, not the whole file.

Size doesn't grow alarmingly at all and it takes less than 20mins to make a differential. My computer turns on automatically at 5:30am to take the backup so I never feel it.

I use my backup strategy for my system partition C:\ and I backup to the same hard drive to a different partition. This allows me to restore my computer quickly, if I screw up my OS with a software like lets say a registry cleaner.

This is the reason I have a limited space and also why I prefer incrementals, as data on my OS partition changes frequently, I am always installing uninstalling new software and playing around inside windows.

In such a case the size of differentials grow unpredictably and in huge jumps. Furthermore, incrementals take only 1-2 minutes to complete on my system while differentials take a lot longer 10+ minutes usually.

[MarcP]

Originally Posted by Raza0007

I use my backup strategy for my system partition C:\ and I backup to the same hard drive to a different partition.

Won't save you if that one drive goes bad one day, though.

[Raza0007]

Originally Posted by MarcP

Won't save you if that one drive goes bad one day, though.

Yeah, I know but there is nothing important on that hard drive to save. I primarily use the backup strategy as an alternative to windows system restore, but whereas system restore can fail you occasionally, the backup and restore never does.

[MarcP]

Fair enough. A backup strategy is all about what you're comfortable dealing with in terms of strength and weakness of the strategy.

[Brian K]

I use differentials in a similar manner to Marc. Full images monthly and I keep the last 15 differentials.

Different computer I know but my differentials take less than 90 seconds to create and by the end of the month are less than 50 MB in size.

[aladdin]

Originally Posted by Brian K

I use differentials in a similar manner to Marc. Full images monthly and I keep the last 15 differentials.

Different computer I know but my differentials take less than 90 seconds to create and by the end of the month are less than 50 MB in size.

Dearest Brian,

Congratulations on the new title.

Best regards my friend,

[Brian K]

aladdin,

Thanks for your words of encouragement.

[andyman35]

Originally Posted by MarcP

I use Macrium Pro. I run a full backup on the 1st of every months, but keep the previous month's backup and it's last 14 days of differentials until the 14th of the new month. So basically I always have a full month of backups done to a 1TB drive. Never ran out of space.

Excellent strategy there