difference img \ iso

Polytropon freebsd at edvax.de
Fri May 3 00:26:03 UTC 2013

On Thu, 2 May 2013 19:03:00 +0600, Osinnyy Bogdan wrote:
> Hi there.
> I just want to try some freebsd and get stunned by choosing what release I
> should to download\install.
> So I ask you: what difference between iso\img, I mean, If I download
> dvd1.iso and mount it on USB drive => starting installation, what difference
> between this method and by using *.img ? Why am I asking, 'cause dvd1's got
> 3 times more weight, but I never faced with .img when installing windows
> systems.

The difference is "what's in the files".

An IMG is an image of basically _any_ kind of media. It _could_
also be for a DVD or a hard disk. In case of the FreeBSD
installation media it's intended for a USB stick. The image
contains _everything_ that is needed to make the stick usable,
like boot mechanism, file systems and so on. It can carry any
file system(s) required. It's an exact 1:1 representation of
the content that has to go to the media.

An ISO (read: ISO 9660) is also an image, but primarily intended
to be used with CDs and DVDs. It carries an ISO-9660 file system,
typically with a RR (RockRidge) extension, and it can include
a boot mechanism. However, it has "less complicated stuff" in
it. It can still be used as a basis for _creating_ non-ISO-9660
file systems in memory (memory disks).

Both provided installation media data differs in _content_. While
the install DVD has lots of prepackaged software that you can
install, the "bootonly" media obviously does not have this. The
"memstick" file is somewhere in between.

So you would first make a choice on what installation media you
want to use, for whatever reasons (e. g. no DVD drive, or system
cannot boot from USB). Then you would select the appropriate
installation media data file:

	ISO < 650 MB ---> CD
	ISO < 4,7 GB ---> DVD
	IMG ------------> USB stick

Of course the _tools_ you need to use to deal with them are different!
For example, burning a CD or DVD involves the required recording
application, such as cdrecord (CD) or growisofs (DVD), while for
writing the IMG file you'd simply use dd.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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