DDoS on big mining pools: a quick way to 51%? Slush's Pool, the second biggest mining pool around, is currently down, allegedly due to a DDoS attack:


  News
  16.04.2013
  Pool is under DDoS attack. I'm working on recovering the service back to operation.


This means the entirety of its miners are currently offline, and this for sure lowers the difficulty of gaining 51% of the total network hashing power.

Now, I don't know anything about the hardware/software design of mining pools, how many servers do they employ to centrally manage all miners, how much bandwidth do they have, etc.; but I'm quite sure that nuking one of them would require a lot less computing power than actually obtaining more than 50% of the total Bitcoin network hashing power under its normal operation.

Thus, the question: aren't big mining pools a critical point of failure for the Bitcoin network? If a malicious attacker was to place several of them offline, all of their miners would be instantly disconnected, and then a not-even-so-big mining farm (or maybe a rival pool which engineered the attack in the first place...) could easily overcome the whole network.

How much likely is such a scenario?
How can it be avoided?
Should the Bitcoin community invest more into protecting pools, or, better, make a joint effort into moving from a "few big pools" model to a "many little pools" one, in order to be safer from similar attacks?
There's no cooperation involved in mining, and they won't be trying the same hashes because (for example) they have different transaction pools and (possibly) different destination addresses. Mining pooling is just like non-pooled mining, except that the revenue is spread over time instead of getting blocks of 25BTC.

Even when the pooled miners have a backup set that sends them to the largest pool (BTC Guild), that's acceptable for short periods of time. But miners are still people, and if something like that happens they'll quickly correct the issue.