Pool Question: Hashrate distribution and chance to find a Block

[peoples]

Hey guys,

lets face the following scenarios:

Scenario 1:
* 3 miners each 10 TH/s connect to one Pool Node.
* One work template for all connected miners.  (Work template = mining.notify in stratum -> Merkle branch, Coinbase 1/2, ...)
* 3 different nonce for the given work template

10T ---------> |                   |
10T ---------> |POOL Node 1|
10T ---------> |                   |

Scenario 2:
* 3 miners each 10 TH/s connect to different Pool Nodes.
* Three different work templates for three miners. ( 3x different Merkle branch )

10T ---------> |POOL Node 1|
10T ---------> |POOL Node 2|
10T ---------> |POOL Node 3|

In both Scenarios the pool nodes belong to the same pool operator and the miners to one customer.

The question: Is the chance to find a block in both scenarios equal or not ?

Short: 30THs hashing on one work templates vs 30THs - 3x 10THs hashing on three different work templates.

[kano]

Each single hash is independent of every other hash and has the same chance of finding a block.

Network Difficulty x 2^32


So if you do 2 hashes it doubles your chance.
If you do 10^12 hashes, it 10^12 times your chance.

Doesn't matter if it's 2 miners or 1000 miners.
It only matter how many hashes you do to determine the 'chance' of finding a block.
It's pseudo-random, so it doesn't mean you 'will' find a block, just you have a given chance of finding a block.

Try reading ... https://bitcoin.it/


... and this probably belongs in Mining Support since it actually has nothing to do with pools.
https://bitcointalk.org/index.php?board=40.0

[peoples]

alright. Thanks

So as a pool operator/developer one of the most important things is to make sure that every single miner connected to the pool gets different work. ?
Which is controlled by the nonce/extranonce  each miner gets, right ?

For my understanding , nonce itself is to small for modern miners anyway and overflows under a second. So miner starts changeing extranonce, which is also just a number that will be incremented?
Question: How is guaranteed that every single miner realy does unique work. ?  How is secured that each miner changes nonce and extranonce values differently to make sure no duplicated shares are created.

[kano]

...
alright. Thanks

So as a pool operator/developer one of the most important things is to make sure that every single miner connected to the pool gets different work. ?
Which is controlled by the nonce/extranonce  each miner gets, right ?

For my understanding , nonce itself is to small for modern miners anyway and overflows under a second. So miner starts changeing extranonce, which is also just a number that will be incremented?
Question: How is guaranteed that every single miner realy does unique work. ?  How is secured that each miner changes nonce and extranonce values differently to make sure no duplicated shares are created.

The coinbase transaction is what differs for every miner.

Stratum sends a different, incomplete coinbase transaction to each miner.
https://bitcointalk.org/index.php?topic=557866.0

Every pool will have a different coinbase for the simplest reason: no pool wants to send their block reward to another pool.
However, if the pool has 2 or more different work generators (i.e. 2 or more different work servers) they of course must ensure that the coinbase is different on them.

Each miner on the same pool gets a slightly different coinbase from the pool work generator.
If not, then the pool luck will drop - and no pool wants ... e.g. 50% luck coz they always send the same work to two different miners.