Over the last two days, some users have reported on the Grin forum that the Chinese mining pool SparkPool is controlling almost 60% of the total hashrate of the crypto, significantly raising the risk of a 51% attack.
According to some statistics websites, SparkPool currently holds about 60% of the total hashrate on the Proof of Work Cuckaroo29, the PoW intended for Grin’s GPU mining.
Clearly, SparkPool is also active in the ASIC friendly PoW mining, even if for now this PoW is limited only to video cards with at least 11 GB of video memory since ASICs are not available for Grin mining. ASICs, in fact, will be delayed in arriving, considering the recent announcement of Innosilicon.
Fortunately, for now, the ASIC Friendly PoW Cuckatoo31+ boasts a very low hashrate and therefore a lower role in network security compared to the Cuckaroo29 PoW, dominated by video cards and hence by the majority of miners.
In any case, even with Grin’s mining on the Cuckatoo31+ PoW, SparkPool controls most of the hashrate.
Currently, Grin’s network with PoW C29 boasts a hashrate close to 1.4 MGps, while the network with PoW C31+ reaches about 137 KGps. This is a figure that is much lower.
The SparkPool mining pool holds the majority of Grin’s hashrate
As a confirmation that most of the hashrate is controlled by the mining pool SparkPool there is also the percentage of newly mined blocks. In fact, observing the statistics on a weekly basis, it is possible to observe that 53% of the blocks mined in the last seven days come from the SparkPool mining pool.
The second most used pool is F2Pool, which holds about 24% of the network hashrate. Unfortunately, in the last months, some Grin mining pools have literally disappeared, thus concentrating the coin miners on the two main solutions.
Moreover, SparkPool offers rather low fees compared to the competition (1% vs 3%), thus attracting even more small miners from secondary pools.
However, although it is very unlikely to see a 51% attack on the currency, for Grin’s sake the miners should better distribute their resources on the main mining pools, so as to avoid that the entity that controls and manages SparkPool can use the hashrate of the various miners for malicious purposes.
In the past SparkPool had several times exceeded the threshold of 51% of the total hashrate, but fortunately, there has always been a redistribution, albeit minimal, of resources, which has brought back the mining pool to values just under 50%.