On Tue, May 12, 2015 at 7:38 PM, Jeff Garzik <jgarzik@bitpay.com> wrote:
> One general problem is that security is weakened when an attacker can DoS a
> small part of the chain by DoS'ing a small number of nodes - yet the impact
> is a network-wide DoS because nobody can complete a sync.

It might be more interesting to think of that attack as a bandwidth
exhaustion DOS attack on the archive nodes... if you can't get a copy
without them, thats where you'll go.

So the question arises: does the option make some nodes that would
have been archive not be? Probably some-- but would it do so much that
it would offset the gain of additional copies of the data when those
attacks are not going no. I suspect not.

It's also useful to give people incremental ways to participate even
when they can't swollow the whole pill; or choose to provide the
resource thats cheap for them to provide.  In particular, if there is
only two kinds of full nodes-- archive and pruned; then the archive
nodes take both a huge disk and bandwidth cost; where as if there are
fractional then archives take low(er) bandwidth unless the fractionals
get DOS attacked.