Let’s Talk About DAG
DAG is a dataset over 1GB in size used by Dagger Hashimoto algorithm (Ethash) to find block solutions in the blockchain. The main coin for Ethash, of course, is Ethereum. However, there are many others: Ethereum Classic, Musicoin, Ubiq, Daxx, Whale, Pegas, Expanse, Dubaicoin, Soil, etc.
When launching the miner, it is the DAG file which uploads into the graphics card memory. Let’s take Claymore’s miner as an example:
Over time DAG file size increases, which happens every 30,000 blocks and is called an epoch change, so each epoch corresponds to a specific DAG size.
To find out your current DAG size, we recommend using this website: https://investoon.com/tools/dag_size. It shows the current DAG size for main Ethash currencies calculations is based on the block number.
Remember that each block corresponds to a specific epoch, and each epoch corresponds to an exact DAG size.
DAG size is calculated based on the specific algorithm, which you can find here and you can check for yourself to see if it really works or not. We’ve tested it – and it does work. By the way, all the DAG values have been calculated and organized a long time ago, so you can use them at this extract.
Every Epoch DAG File Size Increases by 8 MB
The block time differs from coin to coin: ETH – 30 sec, ETC – 15 sec, EXP – 90 sec. That means that Ethereum Classic reaches 30,000 blocks 6x faster than Expanse. That’s why ETC’s current epoch is 151 (DAG=2,18GB), while that of EXP is only 25 (DAG=1,2GB). Well, we have to admit that it’s not fair to compare those two, as the latter came out a bit later.
Let’s take a look at the Ethereum blockchain.
- The current block time is 30 seconds.
- It takes 900,000 seconds (30 seconds × 30,000 blocks) to change an epoch (900,000 ÷ 60 ÷ 60 ÷ 24 = 10.4 days).
- At the time the article was written the last ETH block was 4,322,994, the current epoch was 144 and DAG the size was 2,134 MB.
- When the block #4,350,000 is reached, the epoch will change to 145, and the DAG size will grow to 2,142 MB.
This result is supposed to happen in 27,000 blocks (around October 9).
First, Vitalik & Co. were planning to launch the so-called Ice Age and the block time was supposed to increase gradually. However, according to the latest news, it will be the other way round. Ice Age is going to be delayed for a year and a half, while the block time is expected to go down to 14 seconds in October 2017, that means epochs would change every five days, and the DAG size would increase by 8 MB.
When Will GPU Stop Mining Ether?
It all depends on the graphics card memory.
2GB GPUs stopped working for Ethereum blockchain in November/December 2016. The dying process started mainly after epoch #93 when the DAG size reached 1.73 GB.
The thing is, some part of the memory usage is a buffer, so you can’t use 100% of your card for DAG. It’s not difficult to check – below you’ll see the memory usage by Claymore on the laptop’s graphics card, epoch #144:
Now the card is using 2.3 GB, which is 200 MB more than DAG size (2.13 GB). If there is a monitor connected to the graphics card, it will take up another 150-200 MB.
Supposing that soon the ETH block time will be 14 sec and will remain stable, 3GB graphics cards will begin slowly dying away in about 400 days, that is, at the end of 2018. The math is pretty simple, check it out yourself:
- The 3GB card has around 650 MB left.
- 650 MB ÷ 8 MB (DAG’s increase per epoch) = 81 epochs.
- Each epoch: 14 × 30,000 ÷ 60 ÷ 60 ÷ 24 = 4.86 days.
- 81 (epochs left) × 4.86 (days per epoch) = 394 days.
4GB cards have almost three years left, so, for now, their owners have no reason to worry. By that moment everything might change multiple times because blockchain technology evolves fast.
Don’t worry if your graphics card lacks memory and can’t mine Ethereum or Ethereum Classic. Many Ethash currencies still work with 2GB graphics cards, as their epochs are considerably low although Ubiq – epoch #8, Expanse – epoch #25, Musicoin – epoch #37. Their DAG sizes are slightly over 1GB at the moment. Moreover, these currencies may often be more profitable than Ethereum – check out Whattomine.