Alternative cryptocurrencies that reduce disk space?

[kkon]

One of the problems in cryptocurrencies starting with bitcoin is having to store the (large) blockchain which makes decentralization harder.

Which cryptocurrencies and technologies tackle this and how efficiently?

How effectively is sharding and/or pruning applied?
Any experience?

[turingox]

I think you could start with reading some more about Dogecoin - I can't tell you details from memory however, there are multiple sources out there that can broaden your perspective, and direct you towards other blockchains alike.

[Rath_]

You don't have to run a full node to use Bitcoin. You can either use a SPV client (e.g. Electrum) or prune your node. Bitcoin blockchain is not as big as Ethereum's (most of its nodes are pruned ones). What we are currently trying to do with Bitcoin is moving some of transactions off-chain so that they could be made instantly and cheaply while putting less stress on the network. The Lightning Network, Liquid and RSK are examples of such solution.

Sharding is a bit complicated and it won't be implemented anytime soon. You can learn more about it here. The author of this text used Ethereum as an example.

[mk4]

One of the problems in cryptocurrencies starting with bitcoin is having to store the (large) blockchain which makes decentralization harder.

This is one of the reasons on why people are against bigger blocks(BCH).

Which cryptocurrencies and technologies tackle this and how efficiently?

While I don't have an answer to your question, I'm pretty sure there are a few out there. The ding is though, while some are smaller in size(due to design or due to only a few people using the coin),  there are drawbacks. Some are centralized, some are unsecure in general, etc.

I think you could start with reading some more about Dogecoin - I can't tell you details from memory however, there are multiple sources out there that can broaden your perspective, and direct you towards other blockchains alike.

Probably this, but just take note that Dogecoin is only a memecoin. It's only made as a joke and not to be taken seriously.

[aplistir]

One of the problems in cryptocurrencies starting with bitcoin is having to store the (large) blockchain which makes decentralization harder.

This is one of the reasons on why people are against bigger blocks(BCH).

The blockchain size problem is actually quite easy to fix. And I bet it will be fixed for bitcoin sooner or later in the future. (probably much, much later    )

Easiest solution is to have some system, where "enough" full nodes verify and sign the whole blockchain state for eg. block 550000, and save all the previous data from the blockchain to a separate file, that is made available to anyone who wants it. (so the data is not lost)

Then take the state of block 550000, which is a list of all the inputs and scripts that a pruned node would keep, which is only a few Gb:s and use that as a base point that will be given to all new nodes.
 
This way we would strip all the historical data from the blockchain, but it would not be lost if some archive sites would save them forever somewhere.

Actually this is what should have been done every time a new coin was branched from Bitcoin. Why did they choose to copy the whole blockchain and not just the current state of it? Beats me. 

[pooya87]

One of the problems in cryptocurrencies starting with bitcoin is having to store the (large) blockchain which makes decentralization harder.

This is one of the reasons on why people are against bigger blocks(BCH).

The blockchain size problem is actually quite easy to fix. And I bet it will be fixed for bitcoin sooner or later in the future. (probably much, much later    )

Easiest solution is to have some system, where "enough" full nodes verify and sign the whole blockchain state for eg. block 550000, and save all the previous data from the blockchain to a separate file, that is made available to anyone who wants it. (so the data is not lost)

Then take the state of block 550000, which is a list of all the inputs and scripts that a pruned node would keep, which is only a few Gb:s and use that as a base point that will be given to all new nodes.
 
This way we would strip all the historical data from the blockchain, but it would not be lost if some archive sites would save them forever somewhere.

Actually this is what should have been done every time a new coin was branched from Bitcoin. Why did they choose to copy the whole blockchain and not just the current state of it? Beats me. 

what you are describing sounds like "pruned mode" that are bitcoin nodes are already using. there is also a service bit for it in BIP159 indicating that you have at least 2 days worth of blocks!

what OP is asking i believe is mostly about increasing the efficiency of blocks or at least it should be. throwing out some parts of blockchain is not changing anything, it only means you no longer have the full blockchain. and sharding isn't a solution either! these are more like "solutions to help people like something they can call node but isn't a full node!"
if you can find a way to make transactions actually take up less space then you have reduced disk space consumption.

[jlroberts]

One of the problems in cryptocurrencies starting with bitcoin is having to store the (large) blockchain which makes decentralization harder.

This is one of the reasons on why people are against bigger blocks(BCH).

The blockchain size problem is actually quite easy to fix. And I bet it will be fixed for bitcoin sooner or later in the future. (probably much, much later    )

Easiest solution is to have some system, where "enough" full nodes verify and sign the whole blockchain state for eg. block 550000, and save all the previous data from the blockchain to a separate file, that is made available to anyone who wants it. (so the data is not lost)

Then take the state of block 550000, which is a list of all the inputs and scripts that a pruned node would keep, which is only a few Gb:s and use that as a base point that will be given to all new nodes.
 
This way we would strip all the historical data from the blockchain, but it would not be lost if some archive sites would save them forever somewhere.

Actually this is what should have been done every time a new coin was branched from Bitcoin. Why did they choose to copy the whole blockchain and not just the current state of it? Beats me. 

Are there currently any coins doing this?

[kkon]

Which cryptocurrencies and technologies tackle this and how efficiently?

While I don't have an answer to your question, I'm pretty sure there are a few out there. The ding is though, while some are smaller in size(due to design or due to only a few people using the coin),  there are drawbacks. Some are centralized, some are unsecure in general, etc.

Thanks for answering this. I'd like to know more. Are there specific coins that are well or less well known?

what you are describing sounds like "pruned mode" that are bitcoin nodes are already using. there is also a service bit for it in BIP159 indicating that you have at least 2 days worth of blocks!

what OP is asking i believe is mostly about increasing the efficiency of blocks or at least it should be. throwing out some parts of blockchain is not changing anything, it only means you no longer have the full blockchain. and sharding isn't a solution either! these are more like "solutions to help people like something they can call node but isn't a full node!"
if you can find a way to make transactions actually take up less space then you have reduced disk space consumption.

Thanks, this is helpful. I am actually asking for both. Any way to reduce disk space, that can be reliable of course.
I think that decentralization is more meaningful if all nodes are full nodes.
At the same time, if full nodes can safely discard data, in whatever - proven - way, I'm all for it.

Then take the state of block 550000, which is a list of all the inputs and scripts that a pruned node would keep, which is only a few Gb:s and use that as a base point that will be given to all new nodes.
 
This way we would strip all the historical data from the blockchain, but it would not be lost if some archive sites would save them forever somewhere.

Thanks. Are there known coins where this is applied recurringly?
Is there any known impact in security?

You don't have to run a full node to use Bitcoin. You can either use a SPV client (e.g. Electrum) or prune your node. Bitcoin blockchain is not as big as Ethereum's (most of its nodes are pruned ones). What we are currently trying to do with Bitcoin is moving some of transactions off-chain so that they could be made instantly and cheaply while putting less stress on the network. The Lightning Network, Liquid and RSK are examples of such solution.

Sharding is a bit complicated and it won't be implemented anytime soon. You can learn more about it here. The author of this text used Ethereum as an example.

Sounds helpful. Thanks! I am wondering about the off-chain solution and whether it could impact decentralization in any way.
Is there any live implementation of sharding somewhere?