How to Choose a Wallet for Grin

GRIN crypto network has always had a problem with wallets. Sadly, the developers don’t have their own GUI wallet. Neither for desktop PCs nor for mobile devices. If you want your coins to be as safe as possible, you must opt for a wallet with a command line (that is, without visual interface), learn commands and so on. For an average user, this is a nightmare. There is also an open source grin++ wallet, but it is not compatible with all wallet versions.

In order to perform a transaction in GRIN, wallet versions must coincide. If one user has a new version, while the other has an older version, it is unlikely that the transaction will go through.

As a mining pool, we must always choose the wallet version that works with as many other wallets as possible. Usually, we strongly recommend not to store coins on crypto exchanges. However, in the case of mining GRIN, we recommend to use addresses generated by crypto exchanges. Why is it so?

In the case of GRIN, both sending and receiving wallets must be online at the moment of transaction, otherwise, it will not go through. Most cryptocurrencies allow you to simply send coins to a certain address. And it doesn’t matter whether a user is online or whether he has a private key from this wallet. You can send coins abroad to a complete stranger even if he didn’t ask for it.

2Miners Pool Payout System

2Miners payouts are automatic. As soon as a miner reaches the minimum payout, the coins will be transferred to his address. The amount differs from coin to coin. For GRIN it is 3 coins.

Then in the course of two hours, the pool sends the reward. The system is fail-proof. The exception is BEAM and GRIN cryptocurrencies, where both sending and receiving wallets must be online. If a receiving wallet is offline, the pool will try to send the reward every two hours until it succeeds.

Recommended Cryptocurrency Exchanges

Every cryptocurrency on 2Miners pool has a page with settings where we also list recommended wallets and crypto exchanges. Again, we don’t recommend using exchanges to store funds, but many of our users still like it. As a pool, we can easily send payouts to any type of wallet. I doesn’t matter who owns the wallet, a miner or an exchange, that is not our business.

How do we choose which exchanges to recommend? First of all, nobody pays us for placement on the assistance pages mentioned above. We choose top-rated exchanges. We test platforms personally and if they work properly, we list them. We are not responsible for neither hardware wallets nor exchanges. Their developers are responsible for them. But we do take responsibility for our work because we value our reputation.

As they said at the beginning of GTA2: “And remember, respect is everything”.

GRIN has a long list of recommended exchanges. It’s because not all crypto exchanges support the automatic reception of GRIN coins, so we made sure to list all compatible exchanges. When GRIN was launched, there were only two such exchanges, then there were eight. It doesn’t mean that we personally like all of them. We just tested them and notified our miners that they work properly.

Transactions in GRIN Network

GRIN is a safe and “hidden” blockchain. GRIN doesn’t have a so-called blockchain explorer that provides information about the network operation. Transactions are hidden from unwanted eyes. Only the sender and the recipient can check whether the transaction went through (provided they have a transaction ID).

Cryptocurrencies don’t have customer support or “cyber police”. It means that if your funds were stolen or you sent a transaction to the wrong address, no one would be able to help. In traditional blockchains like Bitcoin or Ethereum you can always go to the blockchain explorer and find out who is right and who is wrong. You will see who received coins, how many, from which address and when.

So let’s take another look at the two main features of transactions in GRIN:

1. A receiving wallet must be online for the transaction to go through.
2. There are no blockchain explorers. It is impossible to check whether someone’s transaction was really performed.

Bitforex Issue

On January 9, 2020 the pool sent 59.08800 Grin to the Bitforex exchange address as a reward to the miner. Transaction ID (Txid) is 11476547-b7ee-4531-7adc651dee0c. The funds haven’t reached the exchange. We always try to help our users, so we contacted the exchange.

First, we tried to find out what happened through the official Bitforex Telegram channel. We got in contact with administrator Kate. Honestly, her answers were embarrassing. It was clear that she was completely incompetent in the matter. We have tried a few times to find contact information of senior managers, but every time we were refused with an inconclusive reply.

1. Here she tells us that the transaction was 4 GRIN instead of 59.08800 GRIN and attached the following screenshot.

   

   After a simple comparison of transaction IDs, it becomes clear that this is not the transaction we were asking about.

2. Then she tells us that on January 8 Grin deposit was closed for one day. First of all, the transaction we are talking about was not performed on January 8, but on January 9. Second, the transaction can’t go through if the receiving wallet is offline. You can’t send coins into thin air. If it were possible, we wouldn’t have a TX ID.
3. 3. And here is the funniest response of all. Quote: “Hello, unfortunately, we haven’t received this transaction, we can’t find it in our system, so the coins can’t be transferred. Screenshot is attached.”

   

   Why is it so funny? Because we already sent this very screenshot to her. Previously a 2Miners employee sent this screenshot from our wallet. She saved it and then sent it to another 2Miners employee as if it were a screenshot from the Bitforex exchange wallet.

   That’s right, the exchange employee saved our screenshot and resent it to us as proof making it seem like it was sent by the tech department.

   Our discussion ended with the following quote.
   I am sorry that you were not able to get in contact with the team. I am sorry for the user, I really did everything I could, my only responsibility is to quickly pass information to the tech department. And over the course of a long period of my work this is the first time when coins are not transferred. If the coins were sent successfully, the exchange would transfer them to the user with a probability of 1000%. I am sorry, but I don’t have access to any technical details.

   

   As a rule, exchanges always manage to find coins that belong to users and in case of a problem they transfer them provided you have a TX ID. On the contrary, the employees of the platform refused to do so saying that they didn’t receive any coins.

   So we thought that maybe it was just a misunderstanding caused by incompetent employees, translation difficulties, etc. We decided to try again. We wrote to support@bitforex.com – the official tech support. Six days with no answer. Nothing at all.

   Then we wrote to the official tech support through their helpdesk. Five days – no answer. We only got an automatic notification that our message had been received. But it was all in vain.

   Who Is to Blame and What Is Next?

   The answer is simple – we don’t recommend using Bitforex exchange. If the exchange can’t admit its fault and can’t reply to the message for five days, and the administrators of the exchange chat write complete nonsense, then you can’t trust your funds to such a platform.

   We have deleted Bitforex from all recommendations on 2Miners pool. It is not about money, it’s about professionalism and respect to clients. Our miner has spent one month trying to solve the problem, but hasn’t received any feedback. Same happened to us.

   We took this problem to heart. We decided to pay to our miner 59.08800 GRIN lost by Bitforex exchange from our own funds. Unlike Bitforex, we value our reputation.

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MOAC Delisting

We’ve stopped MOAC pools on February 3rd due to the network problems. All the situation was covered in our post MOAC Network is Under Attack. We’ve observed multiple denial-of-service attacks on the network. Blockchain was split many times. Unfortunately, MOAC blockchain developers have done nothing in nearly one month so we have decided to delist MOAC coin from the pool.

2CryptoCalc Mining Calculator Updates

Mining Profitability Calculator 2CryptoCalc is becoming better everyday. This month we’ve added such features:

• GPU Memory check. If GPU is not able to mine a specific coin, this coin is not shown in the list;
• Specific GPU and algorithm pages;

We are working on GPU ranking page, new design and many more awesome features.

2Miners Pool Monitoring System

Our CTO Erik Van Daal has written amazing post Monitoring for Health. He thoroughly explains many problems encountered by the mining pools and how do we monitor them. Blockchain splits, DDOS attacks, Orphan blocks and more problems are described in this article.

Antminer E3 Problem

Very popular Ethash ASIC miner Antminer E3 has stopped mining Ethereum Classic this month. It will stop mining Ethereum in April. This has happened due to the ASIC memory limit. Antminer E3 can not store the constantly growing DAG file anymore. Read more in our post Antminer E3 Stops Mining Ethereum Classic, Just Over a Month Remaining for Ethereum.

Innosilicon A10 Specs and Setup

We’ve successfully tested newly-built Innosilicon A10 ASIC machines. We’ve upgraded our pools to support these devices.

Innosilicon A10 is 2 times more effective than previously available ASIC’s and GPU mining rigs. It consumes 750W providing 500MH/s hashrate on Ethash mining algorithm. Check Innosilicon A10 Specs, Profitability and Setup Guide.

Nicehash and ASIC Stratum Protocol Updates

We have updated our pools to support native NiceHash and ASIC-compatible Stratum protocols. This allows our miners to be more efficient both using Nicehash rented hashpower and ASIC’s. Why is this important? Read here NiceHash and ASIC-compatible Stratum Protocols on 2Miners.

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What Is a Mining Pool

As you may know, 2Miners are a quite intensive operation: we have almost 40 pools, most of which are specialized software on dedicated physical servers located in three locations around the world.

A moment of clarification: each pool is a combination of four essential components:

1. A cryptocurrency node that hosts the blockchain, submits new blocks found by the pool miners to the network and processes the payouts to the miners.
2. The specialized custom-written pool software that accepts and verifies miner solutions, distributes new computing work and analyzes miner statistics.
3. A high-performance database that accumulates all submitted shares, stores the miner-related statistics and every other relevant data.
4. The Web frontend displays the miner data, graphs, payout history and so on.

As you may guess, any of these four components can face different problems and if any of those fails, it will affect the operation of the pool. How the Mining Pool Works: PPLNS vs. SOLO.

Most Common Mining Pool Problems

The way cryptocurrencies work is by no means error-prone and all kinds of bad situations may occur. Here are the most common ones that we face more or less on a regular basis:

• There is a network split causing the cryptocurrency node to mine on a wrong chain causing rejected blocks and the loss of profit for our miners;
• Due to some bug in the cryptocurrency node the mining process is affected or interrupted;
• There are issues with the network connection between our servers in different data centers around the world (we currently host our servers in Europe, Asia, and America);
• There is a DDoS attack running against our servers by some malicious attackers who try to disrupt the operations;
• The disk or RAM space on one of our servers is low or there is a hardware component fault so there is a risk of losing some data;
• A ghost of Vitalik Buterin is trying to steal some blocks from our ETH pool (okay, just kidding about this one).

We have designated people that are reacting to threats and incidents 24/7/365. But how do those specialists know there’s a problem that needs to be solved?

Enter the Telegram. We use it extensively for our work-related chats, including problem monitoring. Specialized custom-developed bots watch every aspect of day-to-day pools operation and report to us any problems and irregularities. Not every warning means a real problem, so the DevOps team carefully checks each message and reacts to the ones that need attention.

What stuff do we actually monitor? Let me describe in more detail which aspects of the pools are being watched.

Zabbix Monitoring

Zabbix is an open-source powerful monitoring system that can be extended by custom plugins to watch over some custom aspects of each machine we have in operation. Zabbix watches the disk space, CPU and RAM usage, current traffic and network load, the health status of our web frontends and microservices. Also, we have a set of custom plugins that watch over the availability of mining ports, mining luck, and payment issues.

Each incident is tunneled over to a special private Telegram chat and then analyzed and acted upon, if needed.

It is worth noting that we try to keep the CPU load of our servers below 20% to allow for unexpected short spikes in usage and to provide a good mining experience for all of our users. If there is a steady increase in the CPU load that is not going away, it is a good reason to enable backup hardware infrastructure to mitigate the load.

Orphan Blocks Monitoring

Some Ethereum-based cryptocurrencies have a mechanism called “Orphans” for blocks that were mined with the correct solution, but the blockchain network has chosen to pick some other block mined by some other miner or pool because it was mined a few seconds earlier or so; the orphans are usually also rewarded but in smaller amounts. You could find more information on that in our post Orphan, Stale & Uncle Blocks in Bitcoin and Ethereum. In Bitcoin world, term “orphan” is usually used to indicate blocks that have a correct solution, but that were not accepted onto the main blockchain for various reasons (mined later than somebody else, or mined onto an orphaned chain); these are not rewarded.

Either way, an orphan appearing is a reason to do a quick check: are the nodes healthy or they are in the early stages of a split? Is network connectivity stable enough so the solutions are delivered to the rest of the blockchain network as fast as possible?

Blockchain Split Monitoring

So-called “network splits” happen when some network nodes disconnect from each other and start producing a distinct chain of blocks. Once they reconnect, the blockchain chooses one of the chains, making the entire another chain invalid (or orphaned). This is potentially bad for our miners as it means a potential loss of profit. This is why we try to detect these situations as early as possible and try to eliminate them. Chain split could happen accidentally or it could also be a result of a 51% attack.

A special monitoring bot takes various sources of information (our own nodes, some well-known explorers on the Web, some other pools’ data, etc) and estimates whether our cryptocurrency nodes are in the correct chain or not. If not, an alert is emitted so our engineers can verify it. It is worth mentioning that an official coin explorer can often be itself in a split, so we trust pools’ data more (after all, it’s the source of new blocks so they often have more accurate information).

Other Emergency Mining Pool Monitoring

The error conditions above are not nearly the exhaustive list of what can go wrong with a cryptocurrency mining pool. There are lots of times when due to programming bugs the cryptocurrency nodes report an error and stop working, requiring a restart. All of these cases are handled by a separate bot. So whenever something that’s not in the predefined list goes wrong, this bot will pick it up and report to the DevOps team. Then some issues are as easy as “restart the node”, and some require some thoughtful investigation sometimes resulting in a bug report to the cryptocurrency maintainers or even a pull request to fix the bug.

Miner’s Monitor

Last but not least, while all of the things mentioned above are private and used internally, we do have a Telegram bot that’s accessible for any miner: @Pool2MinersBot. It is quite a powerful bot that latches on the same backend as our internal tooling. Not only can it report to you whether one or more of the workers has gone online or offline, but it also notifies when your worker finds a block and provides a useful source of information for the statistics of your mining operations.

I believe a professional and well-thought process of monitoring existing resources is key to a successful mining pool business. While almost anyone with mediocre programming background could assemble a simple pool using the open-source software, making it handle a big load and do so in a performant manner, while watching for all the issues a pool may have, takes a team of highly skilled professionals, just like with anything else. We at 2Miners care about our users as our own income depends on how well we do so.

That’s it for now. Peace!

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