Never thought about it this way

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Never thought about it this way

Postby AlanD » Tue Oct 04, 2016 8:51 am

I never thought about the imaging process in this way, so I am asking:
is this the nuts and bolts behind what actually happens when one makes
an image using IFW or IFD or IFL? [see below]

[source: AskLeo Newsletter #620]:

Data – and only data – gets placed into an image file. It includes all
of the boot information, partition information, and overhead
information, with your files and folders, and compiles it all into an
image file. Since it doesn’t contain any of the drive marked as free
space, an image is typically much smaller than the actual size of the
drive you’re backing up; it’s proportional to how much disk space has
actually been used.

A full-image backup has two main differences from a clone:

Free space is completely ignored.
The layout of the files on the disk is completely ignored.

Typically, an imaging program copies one file at a time. It looks for a
file on C:, copies it to the image file, and moves on to the next file.
That process removes any fragmentation present on the original drive.
The net result is that the back-up file represents a completely
defragmented image. In other words, all of the files are sitting next to
each other, perfectly contiguous. When you restore an image file to an
empty hard drive, all the files come back perfectly defragmented (in
fact, that is one way to defragment a drive completely: back it up to
an image and immediately restore it).

AlanD
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Re: Never thought about it this way

Postby Bob Coleman » Tue Oct 04, 2016 12:48 pm

There are probably different types of images. I'm quite sure that for the type relevant here it is not true that the image is created file by file. It's created used sector by used sector. It does not defragment drives. Restoring an image puts everything back right where it was. (The image programs contain a Compact option which can consolidate used space on a partition, but that's not part of creating an image).
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Re: Never thought about it this way

Postby AlanD » Wed Oct 05, 2016 9:32 am

On 2016-10-04 3:48 PM, Bob Coleman wrote:
> There are probably different types of images. I'm quite sure that for the type relevant here it is not true that the image is created file by file. It's created used sector by used sector. It does not defragment drives. Restoring an image puts everything back right where it was. (The image programs contain a Compact option which can consolidate used space on a partition, but that's not part of creating an image).
>
>
Exactly what I had always thought. Thank you.
AlanD
 
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Re: Never thought about it this way

Postby tas3086 » Wed Oct 05, 2016 11:24 am

Bob Coleman wrote:
> Restoring an image puts everything back right where it was.

I would rephrase it as follows:
Restoring an image puts back the active used sectors, right back where they were. Unused/unallocated/free sectors on the restored drive are not changed because they were not copied as part of the backup.

I understand that there is a image option to backup all sectors, used and unused, but I do not know what it is.
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Re: Never thought about it this way

Postby TeraByte Support(PP) » Wed Oct 05, 2016 3:28 pm

tas3086 wrote:
> I understand that there is a image option to backup all sectors, used and unused, but
> I do not know what it is.

"Backup Unused Sectors"
Paul Purviance
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Re: Never thought about it this way

Postby TeraByte Support » Thu Oct 06, 2016 11:09 pm

an "image" gives you back what it backed up (same sector areas). Anything
else is not really an "image". There can be some differences on restore to
ensure booting works, but overall the files are in the same locations within
the partition. That's why it was called an "image" and made it popular, so
lots of things became an "image".

"AlanD" wrote in message news:12616@public.image...

On 2016-10-04 3:48 PM, Bob Coleman wrote:
> There are probably different types of images. I'm quite sure that for the
> type relevant here it is not true that the image is created file by file.
> It's created used sector by used sector. It does not defragment drives.
> Restoring an image puts everything back right where it was. (The image
> programs contain a Compact option which can consolidate used space on a
> partition, but that's not part of creating an image).
>
>
Exactly what I had always thought. Thank you.

TeraByte Support
 
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