[CentOS] how to convert 7 cd iso images into one dvd image?

[Andre Robatino]

Les Mikesell <lesmikesell at ...> writes:

> If the remote will run rsync, just use that in the first place to get the dvd 
> and use the -P option so it will restart if you don't complete on the first
attempt.

I can't find a mirror that has the 5.2 DVDs, so testing with the i386 5.5 DVD,
using "rsync -avzP mirror.clarkson.edu::centos/5.5/isos/i386/<ISO name> ." to
generate each image.

Going from the CD set to the DVD:

cat CentOS-5.5-i386-bin-?of7.iso > CentOS-5.5-i386-bin-DVD.iso
rsync -avzP \
mirror.clarkson.edu::centos/5.5/isos/i386/CentOS-5.5-i386-bin-DVD.iso .

sent 517767 bytes  received 84526757 bytes  185080.57 bytes/sec
total size is 4185118720  speedup is 49.21

which is about 2% of full transfer size.

Going from the DVD to the CD set:

cp CentOS-5.5-i386-bin-DVD.iso CentOS-5.5-i386-bin-1of7.iso
rsync -avzP \
mirror.clarkson.edu::centos/5.5/isos/i386/CentOS-5.5-i386-bin-1of7.iso .

(repeat commands for discs 2 to 7)

total size is 653910016  speedup is 21.96
total size is 651780096  speedup is 55.61
total size is 661088256  speedup is 33.97
total size is 649381888  speedup is 46.08
total size is 660133888  speedup is 94.81
total size is 668108800  speedup is 273.26
total size is 242888704  speedup is 58.27

Adding up the sizes divided by the speedups, the total transfer is also about 2%
of total size. Going from the DVD to the CDs is a little tedious since you have
to copy a DVD-sized image 7 times; going from the CDs to the DVD it only happens
once.

I was also able to save about half the bandwidth using rsync to go from the 5.4
DVD to the 5.5 DVD (since many of the packages are exactly the same), so it
should help going from 5.5 to 5.6. It probably won't help going from 5.X to 6,
since almost all the packages will have changed.