Higher difficulty pooled mining

Higher difficulty pooled mining is an attempt to allow powerful miners with high hash-rates to mine efficiently while reducing network chatter, therefore saving usage limits and bandwidth for both the miner and the pool operator. In development at this time, this concept is expected to overtake classical 1-difficulty pooled mining in the near future, coinciding with the introduction of ASIC mining. The basic concept is to only accept shares that meet a certain difficulty, so less shares are sent to the pool.

Concept

With rapidly-increasing hashing speeds, miners are rather wasteful in terms of bandwidth. Each share requires submission to the server, which must handle shares from all miners. This can be overloading, and is suboptimal.

Higher difficulty pooled mining saves bandwidth and does not affect the expected return; however, volatility is increased. For powerful miners, volatility should be low even with a higher difficulty, and the bandwidth savings can pay off.

Hypothetically, pools can allow miners to set their own difficulty level. No pool demonstrates this ability yet; however, Eligius may offer this functionality in the future.

Technical details

Communication is done, as with classical pools, with the getwork protocol. However, some mining software does not yet fully support the protocol.

History

Higher difficulty pooled mining originally originated in a SolidCoin pool, but after SolidCoin's closure was forgotten. The concept had previously been discussed, but weak mining hardware made original 1-difficulty mining pools sufficient. After Litecoin's introduction, many Litecoin pools also adopted the concept. The first Bitcoin pool to propose higher difficulty pooled mining was Eligius; however, at the time, this has not yet been implemented. The first pool known to use higher difficulty pooled mining is HHTT, which uses a difficulty of 32.

Support

Pools

Only one pool is known to use higher difficulty pooled mining.

Pool	Difficulty	Power (GhHz)	Type
Horrible Horrendous Terrible Tremendous Mining Pool (HHTT)	32	6	PPS

Software

Main article: Getwork support

Mining software that fully conforms with the getwork protocol are compatible with higher difficulty pooled mining.