Dear CentOS mirror administrators,
There are many mirrors, but few mirrors provides DVD images. I believe most of all mirrors have enough resources to provide DVD images. You always say the master can't provide DVD images for all mirrors without enough resources.
I suggest introducing mirror hierarchy as follows to solve this problem.
Administrators of servers with enough facilities stand as candidates of sub-master server. You may chose at most two or three servers in one country, and allow only sub-masters to access the bunch of master servers. In this case, All masters should provide DVD ISO images.
In my humble estimation, sub-masters should have at least 500 Mbps of effective bandwidth dedicated to CentOS. They should also provide rsync service able to have more than 20 simultaneous connections. The word `effective' means sub-masters should transfer more than 5 Tbytes per day only for CentOS.
As for our server, it can easily satisfy these criteria.
Sub-masters may synchronize with the master each hour. Other mirrors may synchronize with the sub-masters 2-4 times per day.
Sub-masters should properly share the rsync ACL with the masters to distribute new releases secretly in advance.
Please investigate this idea.
Regards,