What caused the dip in block rate in 2011?

[Paul]

I was looking through some blockchain data and I noticed that from mid July to about mid October in 2011 Namecoin experienced a dip in the block creation rate. I have included some plots below. I am new to Namecoin, and I was wondering if anyone knows why this happened?

[biolizard89]

I don't remember if this was at the time you refer to, but prior to merged mining being implemented, someone posted on BitcoinTalk announcing that given the Namecoin difficulty and exchange rate, it was more profitable to mine Namecoin than Bitcoin. All the miners quickly rushed to mine Namecoin until the next difficulty retarget, and then dropped it. As a result, Namecoin's difficulty was aritificially high, which caused a lot of Namecoin miners to quit until it returned to normal (which exacerbated the issue). At this time it would often take hours for transactions to confirm.

This is one of the major reasons why merged mining is so critical to a stable Namecoin blockchain.

[Paul]

I don't remember if this was at the time you refer to, but prior to merged mining being implemented, someone posted on BitcoinTalk announcing that given the Namecoin difficulty and exchange rate, it was more profitable to mine Namecoin than Bitcoin. All the miners quickly rushed to mine Namecoin until the next difficulty retarget, and then dropped it. As a result, Namecoin's difficulty was aritificially high, which caused a lot of Namecoin miners to quit until it returned to normal (which exacerbated the issue). At this time it would often take hours for transactions to confirm.

I didn't know that, thanks for the info.

This is one of the major reasons why merged mining is so critical to a stable Namecoin blockchain.

I noticed the line smoothed out when merge mining was released in October 2011. Perhaps the namecoin hashrate was low enough to be just generally volitile before merge mining.

[phelix]

BitcoinEXpress threatened to attack the Namecoin network. I think he never actually did so but realizing this vulnerability made the Namecoin Devs implement and introduce merged mining. Could be this is the time in between. Also biolizard89's explanation sounds good.