if I0Coin and GeistGeld massive use of RAM is because they are merged mined, why do not all the merged mined coins use that much RAM?
I0coin en GeistGeld have a much shorter block period and they are mostly mined on P2Pool. (what's the GG difficulty?)
Let's look at blocks that only have the coinbase transaction.
- normally mined blocks are about 200 bytes in size (eg block 160099)
- merge mined blocks on a centralized pool are about 700 bytes in size (eg block 160093)
- merge mined blocks op P2Pool (recently) are about 8600 bytes (eg block 840000)
The size of merge mined blocks differs so greatly because they must include the coinbase (generate) transaction of the parent blockchain. The coinbase transactions of P2Pool are generally very big, because every pool member gets paid out individually in that transaction.
Example calculation with IXC.
Difficulty 1775893. Approximate hashrate 2^32*1775893/600 = 12712 GH/s. P2Ppool has at most (if everyone merged mined ixc) 3000GH/s (which is probably a lot less, I don't know, it can be researched)
Average size of block 2000kB (25% P2Pool, 75% other pools). Annual growth 2000*6*24*365 = 100MB.
In my first post, I showed that I0C grows 2.7GB/yr.
Please ask for more clarification if some part of the calculation is not clear.
heck they all merge with Bitcoin so why doesn't bitcoin have the same problem since presumably each time a block of something is merged mined against bitcoin, the merkles of all the coins that got a block at the same time are all in the header of the bitcoin block aren't they?
Bitcoin (the parent chain) blocks only have the root merkle hash of all merge mined blockchains. The size is fixed. It's part of the coinbase txin script, in which miners can place whatever data they please. (size is limited by Satoshi client; it will not build on blocks with too much data in txin).