well, really, it's virtualization[1] that sucks for I/O, not "the cloud" - you could build something very ec2-like without shared disk, in fact, I think ammazon might.

But yeah. Active/active is a far better solution than what I describe, I mean, modulo the extra cash it costs.

[1]well, really, it's sharing spinning disk... the actual overhead of virtualization is pretty low by this point, but if you have two people accessing the same spinning disk? each gets rather less than half the performance they'd have gotten if they have the whole disk to themselves due to the physics of spinning disk and how much worse random access is than sequential. (two simultaneous sequential read/write streams to the same disk can look a lot like random access, depending on queueing.)

DC is unfortunately super expensive for outbound bandwidth ($0.03/GB/mo, or $9.60/Mbps/mo). I'm trying to figure out how to deal with that. On top of $2.25/Hr for a 10GE port ($1620/mo) and EQ $400/mo xcon fee, it adds up fast if you want to be DC'd at multiple locations.