BLOCKCHAIN SHUTDOWN; Troy Norcross, Co-Founder Blockchain Rookies.

Immutability is one of the core principles defining blockchains. Immutability means unable to be changed. But it doesn't mean permanent. If the blockchain is shut down, the data could go away, forever.

SO HOW COULD A BLOCKCHAIN BE SHUT DOWN? In the simplest of terms, a blockchain can be shut down by turning off the entire network of computers which are required to verify and validate the data in the blockchain.

WHAT HAPPENS TO THE INFORMATION IN THE BLOCKCHAIN ONCE IT HAS BEEN SHUT DOWN? The answer depends on what happens to the servers. If the data is erased from all of the servers and there is no backup, then the data is lost.

Shutting down the tens of thousands of computers running the Bitcoin network would be difficult, but it's not impossible. The more nodes, the harder it is to shut down. This is one of the reasons why it is so important to have a large number of globally distributed nodes (computers) supporting a public permissionless blockchain.

For a private blockchain, the number of nodes is typically far smaller making shut down of a private blockchain easier. For some enterprise customers it may be desireable to have a blockchain which only exists for a specific period of time.

Once shut down, can you turn it back on again? Possibly. If there are sufficient nodes with a current copy of the data when the blockchain was shut down, they may be able to reach consensus before resuming the work of adding new data to the blockchain.

The information on a blockchain is considered to be immutable. Immutable does not mean true. Equally, immutable does not mean forever.

Thanks to Richard Jackson t:@rncjackson for asking the question: How do you shut down a blockchain? Get in touch with us info@blockchainrookies.com / Twitter @igetblockchain