[bitcoin-dev] Miners are struggling with blocks far smaller than 750KB blocks and resorting to SPV mining

Luv Khemani luvb at hotmail.com
Mon Aug 17 08:42:44 UTC 2015

Hi all,
  I previously mentioned in a post that i believe that technically nodes are capable of handling blocks an order of magnitude larger than the current blocksize limit, the only missing thing was an incentive to run them. I have been monitoring the blockchain for the past couple of weeks and am seeing that even miners who have all the incentives are for whatever reason struggling to download and validate much smaller blocks.
The data actually paints a very grim picture of the current bandwidth/validating capacity of the global mining network.
See the following empty blocks mined despite a non-trivial elapsed time from the previous block just from the past couple of days alone (Data from insight.bitpay.com):

EmptyBlock /Time since previous block/ Size of previous block(bytes)/Mined by====================================================370165  29s  720784  Antpool370160  31s  50129    BTCChinaPool370076  49s  469988  F2Pool370059  34s  110994  Antpool370057  73s  131603  Antpool
We have preceding blocks as small as 50KB with 30s passing and the miner continues to mine empty blocks via SPV mining.
The most glaring case is Block 370057 where despite 73s elapsing and the preceding block being a mere 131KB, the miner is unable to download/validate fast enough to include transactions in his block. Unless ofcourse the miner is mining empty blocks on purpose, which does not make sense as all of these pools do mine blocks with transactions when the elapsed time is greater.

This is a cause for great concern, because if miners are SPV mining for a whole minute for <750KB blocks, at 8MB blocks, the network will just fall apart as a significant portion of the hashing power SPV mines throughout. All a single malicious miner has to do is mine an invalid block on purpose, let these pools SPV mine on top of them while it mines a valid block free of their competition. Yes, these pools deserve to lose money in that event, but the impact of reorgs and many block orphans for anyone not running a full node could be disastrous, especially more so in the XT world where Mike wants everyone to be running SPV nodes. I simply don't see the XT fork having any chance of surviving if SPV nodes are unreliable. 
And if these pools go out of business, it will lead to even more mining centralization which is already too centralized today.

Can anyone representing these pools comment on why this is happening? Are these pools on Matt's relay network?

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20150817/9304b47e/attachment.html>

More information about the bitcoin-dev mailing list