Why is drive image larger than C;/ drive ?

Thought I'd make a couple different images on my recently built & never used PC. The C: drive is an SSD and the only thing on it is the Windows 10 OS (vers 1909). For starters I made an image using the Windows 10 image function and used a USB HDD.

Properties show the C:\ with 33.7 GB used and the D:\ with the image with 63,2 GB used. Why is the image so much larger than the original? I thought image files were compressed to save space.

idgat said:

I suspect you may have left the ticks on a few boxes to include in the image some partitions/drives that are not part of actual OS.

Imaging program used ... ??

I used the program that came with Windows 10. Figured I'd start with that & then make a backup with Macrium, etc.

There's only one drive in the PC at the moment & it's the SSD with a single partition with the OS. There are no programs installed yet. That's why I used the Windows 10 imaging function.

Is there anything else on the USB attached HDD ?

Mike100 said:

.... Why is the image so much larger than the original?

...I used the program that came with Windows 10. Figured I'd start with that & then make a backup with Macrium, etc.

I have uses both extensively, but stopped using Microsoft's built in imaging after I tried Macrium - it's so much more flexible, configurable and far more reliable.

How did you start making the MS system image? There are two ways to start the process. The first is to set up a back-up and include a system image, the second is to click create a system image.



I suspect you set up a back-up. This backs up files first, then creates a system image. You are in effect backing up twice, which would explain why the used space on your backup HDD is larger than the used space of the C: drive being imaged. You can tell that you have done this by looking at the HDD you backed up to. There will be two new folders on it, one is named WindowsImageBackup and contains the system image, the other has the same name as your PC and contains the files back-up as a multiple set of .zip files.

If you want to just make a system image you should click the 'Create a system image' link. If you repeated this, and there was sufficient free space on the destination HDD, then the previous system image may be retained. This could also explain why your image is apparently larger than the source.

Microsoft's system image backup solution has little if any user-configurable options. You cannot tell how many (if any) previous images will be retained, nor can you set what compression is used. For imaging to an HDD it will use minimal compression. The system image should be close to, but not larger than the used space of the partitions included in the image. This is really frustrating, because it DOES have a high compression mode - but it will only use it when putting the image on DVDs.

Macrium is fully configurable and by far the better imaging solution.

SIW2 said:

Is there anything else on the USB attached HDD ?

The USB drive Is a 1TB HDD in a SATA enclosure. It's a new HDD that's never been used Properties showed a few MB of space used before I put the image on it and I presumed this had to do with allocation or partitioning or similar. But those few MB do not show up now. Only one item shows up, WindowsImageBackup.

The USB drive Properties list it as "TO External USB 3.0 SCSI Disk Device". Any idea why "SCSI" is indicated?

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Bree said:

I have uses both extensively, but stopped using Microsoft's built in imaging after I tried Macrium - it's so much more flexible, configurable and far more reliable.

How did you start making the MS system image? There are two ways to start the process. The first is to set up a back-up and include a system image, the second is to click create a system image.

I selected "Create a system image" because there was nothing to backup.

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FWIW when I look in Computer Management > Disk Management, it indicates

New Volume (D:)
931.51 GB NTFS
Healthy (Primary Partition)

931GB sounds right for a 1TB disk. The available space will be reported as less than 1TB as shown here.

Its a while since I used Windows own backup routine but that said it always worked well for me. I also remember that you couldn't just hover over the backup folder created and see the size of it. You had to dig a bit deeper and I also recollect the successive images it made were either incremental or differential as the size of subsequent images was relatively small.