The current block size debate has brought up an important, albeit often
neglected observation. Full nodes suffer from a tragedy of the commons problem
and therefore are likely to continue decreasing as a percentage of total
Bitcoin nodes. This also results in a vicious circle as more and more people
use SPVs, the burden on existing full nodes will increase even without a block
size increase, which will further reduce the number of full nodes . A few
people have mentioned it in blogs or reddit, but the topic is generally quickly
overshadowed by posts along the lines of "RAISE the blocksize already!".
Full nodes bear the full cost of validating/relaying/storing the blockchain and
servicing SPV clients but gain nothing financially from it, yet they serve an
important role in validating transactions and keeping miner dishonesty in
check. If there were few independent full nodes, it would be possible for 3-4
of the biggest mining pools to collude and do literally whatever they wanted
with the protocol, including inflating the money supply, freezing funds or even
confiscating funds, because who would know? And even if someone running a full
node did voice out, the majority of users on SPV/Coinbase/etc.. would be
powerless to do anything about it and would likely bear with the changes to
protect status quo, just as is the case with current fiat regimes where people
bear with QE/Inflation/bail outs because they are so dependent on the current
system that they would rather tolerate any injustice than to have the system go
down and bring them with it. This is the primary reason why many in the
technical community are against drastic blocksize increases, as this will only
worsen the problem of decentralization as this cost increases. And as long as
full nodes are running on charity, i'm fully in agreement with the conservative
block size camp.
However, it is important to note that this seems to be an economic problem
instead of a technical one. I cannot deny the argument from the big block side
that technically, the hardware/bandwidth required to run full nodes supporting
considerably larger blocks (4MB-8MB) is not out of reach of many individuals
around the globe. The core issue in my opinion is that of incentive, because at
the end of the day, running a full node is not free and at larger blocks costs
will not be trivial. In my opinion, its perhaps our insistence that full nodes
cant be incentivised that contributes to centralization pressures and
discourages increasing of blocksize even though the technology exists to
support it.
Technically, existing hardware is capable of validating/processing blocks in
the region of an order of magnitude larger than the current limit. Bandwidth
requirements for running a validating full node are also not very high if you
are not mining, as you can afford to wait a couple of minutes to download your
block. This is obviously not the case for miners who need to download new
blocks asap to avoid idle hash power or as has been seen in the recent fork,
SPV mining (which is extremely undesirable for the network). IBLT should help
greatly in reducing the propagation time of new blocks and ease peak bandwidth
requirements. But im not worried about the miners, they are after all being
financially compensated for what they are doing and investing in more
bandwidth(either locally or running a full node remotely) can be seen as a cost
of the business as long as the cost of running a full node is insignificant to
the cost of hashing equipment to keep barriers to mining low.
Before the concept lightning, there did not seem to be any trustless way of
feasibly paying small micropayments to full nodes for their services. However,
with payment channels and lightning, this may no longer be an issue. A node
could advertise it's rates to a SPV nodes upon connection and the SPV could
either agree or look for another node with lower fees. If implemented, fees are
likely to be trivial(few satoshis per request) as competition will drive down
fees close to the cost of running a full node. This should spur an increase in
the number of full nodes and increase decentralization of the network.
I just wanted to float the idea and hear comments/feedback/critiques of this
idea.
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