Difficulty questions

[nalamil]

Hi,

What is the unit of measurement of difficulty in crypto mining?

Given the hash rate of a miner and the (stratum) difficulty, how can one calculate (or at least guess) the expected number of hashes found in e.g. 10 munutes?

The problem I have:  based on nicehash paying numbers for different algos, cryptonightv7 would be almost twice as profitable to mine with, than lyra2z.  But if I mine cryptonightv7, I never find a share, so nicehash believes I'm not even mining.  My performance is not even measurable with that algo.  When I switch to lyra2z, I can find shares, so even if lyra2z pays about half the money (BTC) of what cryptonightv7 would pay, I'm far better of just mining lyra2z.  This knowledge comes from practice.  I would like to know how can one scientifically calculate that mining is not gonna work for a given difficulty.

Is this algo dependent or it can be calculated for all algos the same way?

[adaseb]

It would help if you stated how you are mining these algos? I am assuming you have 1 very old GPU.
From what I remember the min difficulty to submit a XMR share is quite large. I think it's like 5 minutes with a RX 470 GPU.

The reason why it high is because most people mine with multiple GPUs in a rig and they don't want to slow down the server with a share submitted every few seconds so they make it larger. However the share is equally weighted so as long as you mine long enough your earnings will be the same. So submitting 1 share every minute is exactly the same as submitting 1 share every second when it's weight is 60 larger for the minute.

[nc50lc]

There are many factors like total network hashrate, previous block's hashrate, and "Block-time" to consider and these factors differs per coin.
But you can easily "guess" if you have enough hashrate to hit a block (solo mining) based from just the Current network hashrate of the particular coin.

In example, Bitcoin (where mostly all POW coins originated):

• Currently, it has a total of 38,000,000 TH/s
• If you have at least 38,000TH/s, you can expect to hit a block with a chance of 0.1%

Just like that.
Because if you take the whole formula in consideration, you will likely get the same result (in average/few minutes late).By the way, Nicehash doesn't actually solo mine using your hashes, it must have been used together with other miner's hash by a buyer to mine a compatible coin in a pool or personal solo pool.
Maybe your problem isn't the difficulty.