Ethereum delete chaindata
Based on this article, a technical sharing lecture was conducted in DApp Learning. For the Chinese lecture video, please click the second article push. The vigorous development of decentralized applications such as DeFi and GameFi has greatly increased the demand for high-performance blockchains with low transaction costs. However, a key challenge in building a high-performance blockchain is the explosion of storage. The figure below is a chart taken from Etherscan, which illustrates the blockchain data size of an Ethereum full node archived.
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A Blockchain Platform for User Data Sharing Ensuring User Control and Incentives
The simplest way to use a blockchain for recording data is to embed each piece of data directly inside a transaction. Any data within the transaction will therefore be stored identically but independently by every node, along with a proof of who wrote it and when.
For example, MultiChain 1. Each stream has its own set of write permissions, and each node can freely choose which streams to subscribe to. MultiChain 2. While storing data directly on a blockchain works well, it suffers from two key shortcomings — confidentiality and scalability. To begin with confidentiality, the content of every stream item is visible to every node on the chain, and this is not necessarily a desirable outcome. In many cases a piece of data should only be visible to a certain subset of nodes, even if other nodes are needed to help with its ordering, timestamping and notarization.
Confidentiality is a relatively easy problem to solve, by encrypting information before it is embedded in a transaction. The decryption key for each piece of data is only shared with those participants who are meant to see it. Key delivery can be performed on-chain using asymmetric cryptography as described here or via some off-chain mechanism, as is preferred. Any node lacking the key to decrypt an item will see nothing more than binary gibberish. Scalability, on the other hand, is a more significant challenge.
If the purpose of the chain is information storage, then the size of each transaction will depend primarily on how much data it contains.
Data would accumulate at a rate of around 3 terabytes per year, which is no small amount. But with 12 terabyte hard drives now widely available , and RAID controllers which combine multiple physical drives into a single logical one, we could easily store years of data on every node without too much hassle or expense.
And where will each node store the terabytes of new data generated annually? To add insult to injury, if data is encrypted to solve the problem of confidentiality, nodes are being asked to store a huge amount of information that they cannot even read. So how do we solve the problem of data scalability? A hash is a long number think bits, or around 80 decimal digits which uniquely identifies a piece of data. The hash is calculated from the data using a one-way function which has an important cryptographic property: Given any piece of data, it is easy and fast to calculate its hash.
But given a particular hash, it is computationally infeasible to find a piece of data that would generate that hash. Hashes play a crucial role in all blockchains, by uniquely identifying transactions and blocks. They also underlie the computational challenge in proof-of-work systems like bitcoin.
But in order for any hash function to be trusted, it must endure extensive academic review and testing. To go back to our original problem, we can solve data scalability in blockchains by embedding the hashes of large pieces of data within transactions, instead of the data itself.
Even at a rate of images per second, this puts us comfortably back in the territory of feasible bandwidth and storage requirements, in terms of the data stored on the chain itself. Of course, any blockchain participant that needs an off-chain image cannot reproduce it from its hash.
But if the image can be retrieved in some other way, then the on-chain hash serves to confirm who created it and when. Just like regular on-chain data, the hash is embedded inside a digitally signed transaction, which was included in the chain by consensus. If an image file falls out of the sky, and the hash for that image matches a hash in the blockchain, then the origin and timestamp of that image is confirmed. So the blockchain is providing exactly the same value in terms of notarization as if the image was embedded in the chain directly.
So far, so good. By embedding hashes in a blockchain instead of the original data, we have an easy solution to the problem of scalability. Nonetheless, one crucial question remains:. How do we deliver the original off-chain content to those nodes which need it, if not through the chain itself? This question has several possible answers, and we know of MultiChain users applying them all. One basic approach is to set up a centralized repository at some trusted party, where all off-chain data is uploaded then subsequently retrieved.
Even if on-chain hashes prevent the intermediary from falsifying data, it could still delete data or fail to deliver it to some participants, due to a technical failure or the actions of a rogue employee.
A more promising possibility is point-to-point communication, in which the node that requires some off-chain data requests it directly from the node that published it. This avoids relying on a trusted intermediary, but suffers from three alternative shortcomings:. If multiple parties have a piece of data, they should share the burden of delivering it to anyone else who wants it. If a malicious node delivers me the wrong data for a hash, I can simply discard that data and try asking someone else.
For those who have experience with peer-to-peer file sharing protocols such as Napster, Gnutella or BitTorrent, this will all sound very familiar. Indeed, many of the basic principles are the same, but there are two key differences.
Second, the blockchain adds a decentralized ordering, timestamping and notarization backbone, enabling all users to maintain a provably consistent and tamper-resistant view of exactly what happened, when and by whom. How might a blockchain application developer achieve this decentralized delivery of off-chain content? One common choice is to take an existing peer-to-peer file sharing platform, such as the amusingly-named InterPlanetary File System IPFS , and use it together with the blockchain.
Each participant runs both a blockchain node and an IPFS node, with some middleware coordinating between the two. To retrieve some off-chain data, the middleware extracts the hash from the blockchain, then uses this hash to fetch the content from IPFS. First, every participant has to install, maintain and update three separate pieces of software blockchain node, IPFS node and middleware , each of which stores its data in a separate place. Finally, tightly coupling IPFS and the blockchain together would make the middleware increasingly complex.
For example, if we want the off-chain data referenced by some blockchain transactions to be instantly retrieved with automatic retries , the middleware would need to be constantly up and running, maintaining its own complex state. Every piece of information published to a stream can be on-chain or off-chain as desired, and MultiChain takes care of everything else.
No really, we mean everything. Most importantly, all of this happens extremely quickly. In networks with low latency, small pieces of off-chain data will arrive at subscribers within a split second of the transaction that references them. And for high load applications, our testing shows that MultiChain 2. Everything works fine with off-chain items up to 1 GB in size, far beyond the 64 MB limit for on-chain data. Of course, we hope to improve these numbers further as we spend time optimizing MultiChain 2.
When using off-chain rather than on-chain data in streams, MultiChain application developers have to do exactly two things:. Of course, to prevent every node from retrieving every off-chain item, items should be grouped together into streams in an appropriate way, with each node subscribing to those streams of interest.
On-chain and off-chain items can be used within the same stream, and the various stream querying and summarization functions relate to both types of data identically. This allows publishers to make the appropriate choice for every item in a stream, without affecting the rest of an application. With seamless support for off-chain data, MultiChain 2.
With MultiChain 2. A Smart Filter is a piece of code embedded in the blockchain which implements custom rules for validating data or transactions. We look forward to telling you more in due course. Please post any comments on LinkedIn.
While off-chain stream items in MultiChain 2. The list below will mainly be relevant for developers building blockchain applications, and can be skipped by less technical types:. Confidentiality and scalability While storing data directly on a blockchain works well, it suffers from two key shortcomings — confidentiality and scalability.
The hashing solution So how do we solve the problem of data scalability? A question of delivery So far, so good. Nonetheless, one crucial question remains: How do we deliver the original off-chain content to those nodes which need it, if not through the chain itself?
This avoids relying on a trusted intermediary, but suffers from three alternative shortcomings: It requires a map of blockchain addresses to IP addresses, to enable the consumer of some data to communicate directly with its publisher. Blockchains can generally avoid this type of static network configuration, which can be a problem in terms of failover and privacy.
If the original publisher node has left the network, or is temporarily out of service, then the data cannot be retrieved by anyone else. If a large number of nodes are interested in some data, then the publisher will be overwhelmed by requests. Off-chain data in MultiChain 2. The transaction for publishing off-chain stream items is automatically built, containing the chunk hash es and size s in bytes.
This transaction is signed and broadcast to the network, propagating between nodes and entering the blockchain in the usual way. When a node subscribed to a stream sees a reference to some off-chain data, it adds the chunk hashes for that data to its retrieval queue. When subscribing to an old stream, a node also queues any previously published off-chain items for retrieval. These chunk queries are propagated to other nodes in the network in a peer-to-peer fashion limited to two hops for now — see technical details below.
Any node which has the data for a chunk can respond, and this response is relayed to the subscriber back along the same path as the query. If no node answers the chunk query, the chunk is returned back to the queue for later retrying.
The source node delivers the data requested, using the same path again. If everything checks out, the subscriber writes the data to its local storage, making it immediately available for retrieval via the stream APIs. Selective stream subscriptions, in which nodes only retrieve the data for off-chain items with particular publishers or keys. Using merkle trees to enable a single on-chain hash to represent an unlimited number of off-chain items, giving another huge jump in terms of scalability.
Pluggable storage engines, allowing off-chain data to be kept in databases or external file systems rather than local disk. Nodes learning over time where each type of off-chain data is usually available in a network, and focusing their chunk queries appropriately. Technical details While off-chain stream items in MultiChain 2.
The list below will mainly be relevant for developers building blockchain applications, and can be skipped by less technical types: Per-stream policies. When a MultiChain stream is created, it can optionally be restricted to allow only on-chain or off-chain data. There are several possible reasons for doing this, rather than allowing each publisher to decide for themselves. For example, on-chain items offer an ironclad availability guarantee, whereas old off-chain items may become irretrievable if their publisher and other subscribers drop off the network.
For months, I have been using Geth in full mode, where it downloads the entire Ethereum blockchain. I originally tried to do this using a mechanical drive HDD but it was so slow it became obvious it would never actually download the entire chain in my lifetime. Some simple checking on the web noted that a SSD is the only way to get adequate speed to store the chain data in reasonable time. Even with that it took well over two weeks to sync the whole chain. Then when I did not run Geth for a number of weeks, it would take multiple days typically to catch up to the head of the chain. Ethereum mines a new block every seconds or so making it hard to catch up if it takes seconds per block to sync. When the free space went below GB, I became concerned, and when it dipped below 50GB in the last week I decided to look at alternatives.
Using Geth fast sync mode vs full sync
Podcast: Play in new window Download Last week we had the pleasure of talking to Dr. We will try to answer the question of how does GDPR, drafted in a world in which centralised and identifiable actors control personal data, sit within a decentralised world like blockchain? Markus works in the IT law department of CMS Germany with a focus on innovative topics such as blockchain, AI, cyber security and all the data protection issues. Previously to becoming a lawyer, Markus used to work as a software developer. It was enacted in May but only applied from May It replaced the former EU Data Protection Directive with a big difference that it applied directly to the member states of the EU without the need for it to be transformed into national laws. GDPR only applies where personal data is being processed. Personal data is defined as any information relating, directly or indirectly, to a natural living person, whether the data identifies the person or makes him or her identifiable. The key implication is that a person, not a company, can be identified or identifiable.
How to install and run a Prysm Beacon node
Mdm key generator. The same is the case with the Tenorshare 4uKey. Includes Product Support. We stuck on the activation lock or use the MDM key. For products of version 8 and up, this can be done automatically directly from the program if an internet connection is available.
Ethereum Wallet Syncing Problems
Transactional, analytical, full-text search, time series, and more. They are as follows. Although surprisingly CPU-friendly, Hive doesn't sacrifice flexibility or audio quality. Even open source… even if you compile your own Linux, unless you know how to read through the entire source code and confirm its safe, you could potentially be at risk. I've been troubleshooting crashing with my computer for some time now and my windows installation seems to be corrupted or messed up to some extent. Awesome Open Source is not affiliated with the legal entity who owns the "Kriosmane" organization.
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Go to the. If you are already familiar with Linux or just want to do it faster please proceed to bottom of point 1. From here we open a terminal by doing right click under the folder and execute the following command:. From here you can also open the wallet at the same without any problem so you will see the progress or your wallet also. First just to document what I'm doing because some times is hard to remember how I do things and second to share what I'm doing which might be helpful for you.
Ethereum 2. Its primary objective is to increase Ethereum's capacity for transactions, reduce fees and make the network more sustainable. To accomplish this, Ethereum will change its consensus mechanism from proof-of-work PoW to proof-of-stake PoS. Subscribe to our premium newsletter - Crypto Investor.
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How do Ethereum syncing work? The current default mode of sync for Geth is called fast sync. Instead of starting from the genesis block and reprocessing all. You can download the latest 64bit stable release of Geth for our primary platforms below. Packages for all supported platforms as well as develop builds.
As we covered in the Smart Contract Security Mindset , a vigilant Ethereum developer always keeps five principles top of mind:. This piece is primarily for intermediate Ethereum developers. Calls to untrusted smart contracts can introduce several unexpected risks or errors. External calls may execute malicious code in that contract or any other contract that it depends upon. Therefore, treat every external call as a potential security risk. When it is not possible, or undesirable to remove external calls, use the recommendations in the rest of this section to minimize the danger.
In fact I suspect my recent experience is what is keeping it from rising, Ethereum makes me nervous and reluctant to use it everyday. Imagine if a simple eTransfer or Wire from your bank took over a week to initiate? I stress this because I came across many who had sworn off the Ethereum Coin and team because of this confusion where they lost their keys and ultimately their investment and coins. It was updating so slow through the missing blocks that it felt like I was mining the entire blockchain you could literally count 1 by 1 as it was processing or sometimes it would take minutes on a single block.