Windows 7: How big should a System Image be?

Reading this thread got me concerned.

Use whole Disk for Images?

I use a 500GB external drive to store my backups, both System Image and Data Files.

Going by the 30% maximum space Windows allots for System Images my drive can accomodate 150GB. Right now my System Image is 147GB. I believe this is only the most recent system image (see screenshots).

Is 147GB a reasonable size for a System Image or is something wrong? The entire C drive including data takes up about 174GB.

Searching around I see System Images of 25GB. How is that possible?

Many people put data on another partition and image only C.

A C drive containing only Windows and applications often has fewer than 50 GB occupied and an image of C alone typically takes a lot less than the occupied space. My C drive has 28 GB occupied and images of it take up about 12 GB.

Complicating this is the fact that Windows Backup has its own idea of what "system files" are.

I don't use Windows Backup.

Just my opinion:
Irrespective of your imaging software choice, 147 GB is far too large in general.
I think imaging is your ultimate safety net and should be able to be done and restored "relatively" quickly. My rule of thumb would be ~ 50 GB. This will take from about 10 min (USB 3 ext HDD) to 30 min (USB 2 ext HDD).

Your main imaged partition should contain your OS and installed programs. If you have large fairly static data then get it off this partition and back it up independently.

Thanks for the replies.

I am certainly not an advanced user. I used the default settings and stored my data on the C drive. Like millions of other PC users.

So now that I have lots of data when a System Image is made it includes all the data along with system files to the point that my System Image is approaching the limits for my external drive since Windows only allows for 30% of the drive be used for a SI.

It's interesting that in Backup and Restore the way it describes a System Image it seems to imply that only files needed to make windows run will be copied. Obviously that is not true.

Back to my problem. Unless I do something once I have 3GB more of data I will not have enough space on my external drive to accomodate a System Image.

Images typically include EVERYTHING on a partition--whether or not all of those files are needed for Windows to run.

It isn't a major ordeal to use 2 partitions---C for Windows and applications and D for data. It has several advantages, but you'll have to weigh that against whatever reluctance you have.

Any imaging program will image the C partition in its entirety, regardless of whether a given file is needed by Windows. So your data is going to be included in the C image, as long as it is on C.

Other imaging programs don't have the 150 GB limitation to which you refer. But imaging a 147 GB partition will still take up maybe 60 or 70 GB, regardless of what imaging program you use.

I wouldn't go very far out on a limb in expecting an image of my data files to be highly reliable as a backup. But maybe you are backing up your data files through some other method, outside of this image?

I guess I need to make a new partition and move my data to it and then I can image only the (then) smaller C: drive. But honestly I am VERY leery. I have a cursory knowledge about the process but many questions/concerns.

I probably should start a new thread.

When I first install my OS, run Windows Update, Activate the OS and then run an Image using something like Acronis True Image Home 2010, with compression, my image is around 5GB. Once I have my applications that I use installed, my images grow to around 10GB or so. (This contains no data, as I keep my data on a file server at home). Now that I have a few games installed, my images have grown to about 25-30GB.