Can we have a Delta-DVD release

[Andre Robatino]

Andre Robatino wrote:
> Jonathan Steffan wrote:
>> James Gallagher wrote:
>>> Even if the image size is kept below 4.3GB for a single disk, the 
>>> delta download would be welcomed by many.
>>
>> Look into makedeltaiso and applydeltaiso. You end up needing the
>> original (previous release/target) and the delta. This is only useful if
>> the old ISO is left around and you want to end up with a full ISO on the
>> other side. The size of a delta ISO between Fedora releases might be
>> larger then expected. It would be interesting to see some data on this
>> matter.
> 
> One can use a script such as the rawread script at
> 
> http://www.troubleshooters.com/linux/coasterless.htm
> 
> to read an ISO off an optical disc.  So the original ISO(s) can be read 
> off the original install media, if one has those.  Or one can just make 
> a point of keeping the original ISO(s) on the HD after installing.  And 
> even if the size of the deltaiso was 60% or 70% of the full ISO, it 
> would still be worthwhile to many.

Although the applydeltaiso man page doesn't document it, for the input 
ISO argument you can use /dev/dvd after popping in the old DVD (using 
the /media directory name doesn't work), for example

applydeltaiso /dev/dvd Fedora-9_10-i386-DVD.diso Fedora-10-i386-DVD.iso

When I tested this, it took somewhat longer than it did when using the 
ISO on the HD (48 minutes instead of 38).  Still well worth it.  I make 
a habit of keeping the old ISO on the HD, though, so if the old disc 
breaks or something before the new version of Fedora comes out, I can 
just burn a new copy.

If {make,apply}deltaiso are generalized to allow multiple input/output 
ISOs (I filed bug #497205 for this), this won't work anymore, since most 
people only have one optical drive.  But in that case, someone could 
create a user interface that allows reading/writing the discs by popping 
them in, one at a time.

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