A backlog of transactions formed in Bitcoin Cash starting this September 1st following a sudden spike.
Some 600,000 transactions were made on that day, double bitcoin’s 300,000, but instead of them all being cleared, there was a backlog for hours.
It appears there were two reasons for the backlog. First, miners prominently in support of big blocks were using the default soft limit of 2MB.
We can see below that Bitmain’s Antpool and Roger Ver’s Bitcoin pool were both using the client’s default soft limit of 2MB for some hours.
Far more interestingly, an unknown miner limited the blocks to 1MB, while another unknown miner stuck with the default of 2MB.
Both ViaBTC and BTC.top seem to not use the default limit, with other pools changing it later on.
This appears to have been a surprise stress test perhaps to gather information about the pools.
The unknown miner for example appears to be two pools as they use different limits.
The only known pool that uses a 1MB soft limit is Poolin. Some are speculating much of this unknown hashrate is theirs.
Some of the unknown hashrate used the default of 2MB. So that could be one of the known miners or perhaps it’s a new miner.
The default itself is to be expected and it worked as it should. Before the 1MB hard limit was reached in bitcoin, for example, miners had a soft limit of 250kb, which they increased to 500kb and then 750kb once demand reached those levels.
This soft limit acts as training wheels and protects against potential block attacks with it being a mechanism for miners to sort of self govern and self organize in striking the right balance between supply and demand.
If demand nears 2MB, then they can just increase the soft limit, so there’s little unusual or unexpected here save for a 1MB miner would rather be unknown.