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Gerbil First Class
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Does Disk Imaging reduce the size of source disk??

Sun Mar 09, 2014 3:28 am

Hi guys, i want to image my 500GB harddisk and i think 460GB of it is occupied already. Now, i want to put the image file to my 500GB space external disk.. I just wonder if that 460GB size of the image file would somehow reduce? or is compressed?

Other question, how about i am done backuping my system, and i want to use that backup to my new computer, fresh, and still no OS yet.. how would i do it? using my external? OR just like disk cloning, i need to put my new hard disk to a formatted one, and put it there? Is that the process? Thank you so much .... I have only done disk cloning and not imaging yet. But i want to image my current computers because i plan to add more soon... Thanks...
Graphmaster Gerbil
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Re: Does Disk Imaging reduce the size of source disk??

Sun Mar 09, 2014 9:27 am

Most disk imaging software compresses the data when creating the images. That being said, the amount it can compress it do depends on the type of data on it and if that data is compressible. If it was a drive full of video for example, that type of data cannot be compressed. If it is full of docs/exe/windows files/ etc then it can be compressed fairly heavily in most cases.
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Re: Does Disk Imaging reduce the size of source disk??

Sun Mar 09, 2014 10:51 am

General rule of thumb is that documents and databases will generally compress fairly well (50% or more), applications around 25%, and media (audio/video) files don't compress at all. Documents from recent office suites are less compressible (or even uncompressible) though, as many newer document formats are already compressed.

You will want to expand the image onto a new drive to use it.
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Duct Tape Dude
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Re: Does Disk Imaging reduce the size of source disk??

Sun Mar 09, 2014 11:50 am

Typically the image file is written uncompressed.

You could perhaps try enabling file and folder compression on the backup drive if it's NTFS, but otherwise image files aren't compressed by default. Maybe there is some fancy 3rd party software that could compress it before use, or if you have additional disk space you could try throwing it through 7zip or something similar.
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Re: Does Disk Imaging reduce the size of source disk??

Sun Mar 09, 2014 1:00 pm

I use DriveImage XML, free for home use. Can backup a running Windows install using shadow volume locking thingy and is command-line scriptable. Hope I'm allowed to mention it, since it's free.

It supports compression and file splitting. An 80 gig Win7 install, with some software and 1-2 games on the volume, the backup is around 51 gigs on max compression. Takes around 80 mins on my system, due to backing up on an USB 2.0 external HD (would be much faster on a faster drive, on a 2600K CPU).

Backup restore would restore the whole disk, so it's basically a disk cloning mechanism. As long as the target drive is the same or bigger, it should restore the original partitions perfectly. It cannot restore to a smaller drive.

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