A hard fork in the crypto world usually refers to changing the code of a crypto project so that a new blockchain and a new coin is created, where there would now be two versions of the blockchain and coin (similar to Bitcoin Cash splitting off from Bitcoin). Typically, if a user has coins in the wallet of the original blockchain when this type of fork occurs, they will have an equal amount of coins on the new blockchain at the time of the fork, doubling their coins as a result - though the new coins may be worthless or worth very little to start.
Because Sia is open source and is available on Gitlab, anyone can fork Sia or any other part of the project (such as the Sia-UI) and change it or create a new product based upon it. A software project like Sia can also be forked and improved upon without creating a new blockchain and a new coin, such as if someone wanted to improve the official wallet software by making a better user interface. At the time of this writing, there are nearly 500 forks of the basic Sia project on GitHub, though many of them are of old versions and do not create a new blockchain or coin.
If any third party sees fit to do so, though, they can fork the Sia blockchain and create a new coin. Whether or not that version of Sia would gain any support is questionable, as it would also separate all hosts and renters between the two networks - hosts and renters on the third-party fork couldn't communicate with hosts and renters on the main Sia project, limiting utility of the actual Sia storage product significantly on the third-party fork unless it also had a large number of users switch over from the official Sia project.
Forks are listed in chronological order of public announcement. We'd also recommend reviewing the "Blockchains of the Sia Family" on SiaMining, which provides a great overview of the different forks from a comparison perspective.
On October 1, 2018, David Vorick announced the intention to fork the Sia network away from the Blake2b algorithm and to an alternate version of the algorithm that only the Obelisk SC1 ASIC miner can use. The alternate algorithm only accepts hashes made having a nonce value divisible by 1009, which effectively reduces all non-Obelisk units to about 0.1% of their normal hashrate and renders them useless on the Sia network.
The decision to fork was made in response to a "Community Fork" proposal calling for Sia to fork to the alternate algorithm in order to grant Obelisk buyers exclusivity and attempt to mitigate legal troubles for Obelisk. The proposal requested a temporary fork to the alternate algorithm to provide Obelisk ROI, and then a fork back to Blake2b to allow all miners back on the network. It also suggested implementing a development fee from blocks mined in order to fund Nebulous Labs and expedite Sia development.
However, the reasons given for the fork decision by the development team were to essentially punish other ASIC manufacturers like Bitmain and Innosilicon for what the Sia team considers unfair business practices, such as not communicating with the community, not announcing their devices in advance, not releasing batch counts, marking up hardware, and self-mining by manufacturers. The team has stated that the fork will be permanent and will not switch back to Blake2b. They will also not implement a development fee, and will stick to traditional fundraising methods.
The Sia developers say that they will help to support the old chain with the regular Blake2b algorithm if a group of users chooses to continue to maintain and run it. A few groups have come forward with new forks as a result, such as SiaClassic and SiaClassic.
Community Opinion and Controversy
The community reception to this fork has been mixed.
In general, Obelisk SC1 buyers appear to be in favor of a fork because with the other ASICs on the Sia network, SC1 profitability was essentially impossible. Kicking all other units off the network has made mining with SC1s profitable again, so long as another ASIC manufacturer doesn't release a new ASIC with the new algorithm. However, there are doubts by some users that other ASIC manufacturers will build another miner for Sia after being forked off the network, as they might fear being forked off again. Those opposed to Bitmain's business practices are happy to see a blockchain developer finally stand up to what they consider to be abusive ASIC manufacturers, and hope that it will serve as an example to other blockchain projects.
However, there are also many users opposed to the fork who see nothing wrong with the business practices of the third-party ASIC manufacturers, citing them as what any competitive business would do, and question that the reason for the fork is actually as stated. Some argue that third-party ASICs were not attacking the Sia network and were mining normally alongside everyone else, and so they should not be removed from the network. Additionally, the fact that only Obelisks will be allowed to mine on the new Sia fork has raised concerns about conflicts of interest and favoritism, as the Obelisk project is also owned by the Sia developers. Several users believe that Sia is simply upset that their Obelisk project was beaten to market by other fairly competing manufacturers, and the fork is in retaliation for this and is not a good enough reason to fork. You can read more about the Obelisk project's background here.
There are concerns from all sides that kicking all current ASICs off the network and only allowing Obelisks to mine will reduce the hashrate of the network to a fraction of what it is now, making an attack on the network more possible and lowering network security. Some users are concered that Bitmain or Innosilicon will not tolerate being forked off the Sia network, and will retaliate by building superior next-generation ASICs which can mine the alternate algorithm and then deploy them in great numbers - either specifically to attack the Sia network, or simply because they would be profitable again with a large reduction in hashrate. As of April 2019, these concerns appear to be unfounded.
About the Fork
Coins: The fork resulted in multiple chains and networks, as more than one group announced plans to maintain a new fork of Sia. Two Sia releases were made in mid-October: v1.3.5 which was the last Blake2b release, and v1.3.7 which was the new release activating the new chain at block 179,000. Most exchanges and mining pools continue to support the new Sia chain.
Mining: Only Obelisk SC1 units are able to mine the on the main Sia network. Non-Obelisk miners who try to mine on the new chain would see their units stop working, and can switch to one of the other Sia forks maintaining the Blake2b algorithm.
Renting/Hosting: Renters and hosts on the Sia network will likely want to follow the new chain and update to v1.4.0+, as this is the chain which will continue to receive Sia updates and new features from Nebulous.
Sia community member FaustianAGI, the organizer of the "Community Fork" proposal, was not entirely satisfied with Nebulous' reasons for forking or their decision to refuse a development fee as part of the new fork. Joined by several other known Sia community members, the group organized a fork called SiaPrime. While the stated goal of SiaPrime is to build second-layer apps on top of the Sia network, the project has also elected to retain the original Blake2b algorithm, giving miners rejected by the Sia ASIC fork a place to redirect their hashrate.
Community Opinion and Controversy
Community opinion of the SiaPrime project has been positive overall. SiaPrime incorporates many well-regarded community members, promises to retain Siafunds as a condition of Nebulous' support, and has committed to giving Nebulous a grant of a portion of the original token supply of the network.
About the Fork
The SiaPrime network launched late on October 30, 2018, shortly before the Anticompetitive ASIC fork block of 179,000 on the main Sia network. At this point, SiaPrime is not significantly different from the main Sia product in terms of function or appearance. SiaPrime plans to provide tokens on the SiaPrime network at varying tiers based on wallet balances in the near future. More details will be added when known.
SiaPrime does appear to continue to be active with community engagement and recruiting team members, though not much else has come out of the project as of April 2019.
RBZL, the creator of SiaSetup, was among one of ten Sia community contributors to be gifted 54 million XSC tokens at the launch of the Hyperspace network. These tokens were gifted with no strings attached, and SiaSetup attempts to remain neutral in all information provided on any given subject despite this gift.
Hyperspace is a third-party hard fork of Sia which occurred in July 2018. This fork was intended to coincide with the launch of Obelisks in early-mid July, as Hyperspace hopes to offer an alternative to the currently oversaturated mining environment of the official Sia blockchain - however, due to continued Obelisk delays, Hyperspace launched as planned on July 26.
The fork is a result of a difference in opinion regarding management and other strategies around the official Sia product. Hyperspace plans to continue development on their own version of the Sia storage project, as well as to fork the blockchain and create an alternate coin called "Space Cash". The fork uses the Blake2b algorithm so that current mining devices will be compatible with the fork. It also plans to add a development subsidy similar to Decred in lieu of Siafunds. Hyperspace has also launched an open source mining pool, called "Toastpool", which will support multiple coins.
Community Opinion and Controversy
Community opinion of the Hyperspace project is mixed - some users are thankful to have an alternative to the Sia project and a promise of a consumer-oriented experience, while others see Hyperspace as trying to steal Sia's work and rebrand it. There has also been displeasure expressed by Nebulous (the developers of Sia) over Hyperspace's removal of Siafunds from the forked product. The project is in fairly early stages, and overall is not very well known outside of those very familiar with Sia.
With Sia's decision to fork all existing non-Obelisk miners off the Sia network, Hyperspace gained a small amount of attention as miners searched for an alternative to mining Sia. Most miners appear to have stayed on the old Sia version now called SiaClassic.
About the Fork
An "airdrop" occured based on a snapshot of block 161358 of the Sia network, which was mined on July 1, 2018 at about 02:50 GMT. Users who had coins in an official wallet at the time of this block will receive 1 Space Cash for every 10 Siacoin they hold (more information) - if you did not have coins in an official wallet which you control the seed for, you are now too late and you will not qualify to receive Space Cash. Instructions for claiming Space Cash can be found on our companion site at this link. Space Cash will not be visible or be retrieved in the official Sia wallet - only in the Hyperspace app.
As of April 2019, the Hyperspace project appears to be dead, with no significant activity since December 2018.
Shortly after Nebulous' announcement of the Anticompetitive ASIC fork, an organization announced itself as the SiaClassic Foundation with the intention of maintaining a fork of the Sia network. The foundation claims to be registered as a non-profit organization, and it's members have not been significantly involved in the Sia community outside of what appears to be a large-scale mining operation by it's director, Jason Gantt.
As explained in the announcement of the foundation above, SiaClassic appears to be frustrated with the decision of Nebulous to fork. They appear to want to continue to develop the Sia product in line with their own vision, and have claimed to have a first-year budget of over $6 million dollars on Sia's Discord (specifically, "over twice" Nebulous' budget of $3 million to date). However, with no solid announcement of team members outside of a few foundation executives and a PR representative, it's currently unknown how serious the project will turn out to be.
Community Opinion and Controversy
Community opinion of the SiaClassic fork has been overwhelmingly negative.
The initial announcement of SiaClassic claimed to involve known "community members", but none have yet to surface. The biggest reason for the negative reception has been the SiaClassic Foundation's attitude towards their approach of the Sia project. They claim to represent the "original" Sia chain and product, despite the fact that Sia's founder (David Vorick) was the one to announce the Anticompetitive ASIC fork and continues to lead primary development of Sia. SiaClassic claims to be the de-facto Sia v1.3.4, even though they they were not involved in developing or releasing that version.
Innosilicon (one manufacturer of miners Sia chose to fork off) has announced support specifically for the SiaClassic fork, leading some Sia community members to believe that the two are related. The foundation has yet to provide any details on exactly how they plan to build upon and improve the Sia project which isn't already being done by Nebulous or one of the other community forks. SiaClassic also appears to be undetermined as to whether or not they will retain Siafunds in their product, and David Vorick has come out publicly with a negative opinion of the organization for various reasons, including lack of actual community member support and a lawsuit inquiry against Nebulous from Jason Gantt regarding Gantt's mining operation and being forked off the main Sia network.
About the Fork
The SiaClassic Foundation has yet to release any software client of their own, or any details on the plans of their fork, aside from claiming ownership of the older official Sia versions. As of April 2019, the SiaClassic website's "Get Started" section is essentially a copy of Sia's, and offers the old Sia v1.3.4 client for download with no improvements. The SiaClassic project therefore appears to be dead, aside from activity related to Chinese mining interests - nothing to do with the Sia storage product.
- Various forks to fix issues, such as mining difficulty, which cause incompatibility with old versions of Sia
- A "fork" dubbed "SiaCashCoin" which is not actually a fork of Sia, but a junk ERC20 (Ethereum) token with no apparent purpose