On Thu, 5 Jul 2012, James Harper <james.harper@bendigoit.com.au> wrote:
I guess virtualisation doesn't work now any better than it ever has done.
That's the stupidest thing I've heard today. Virtualisation allows you to take a mostly idle workload off of (say) 100 servers and run it on a single server[1] which is well under 100x the cost and power consumption of the 100 servers. Even if that single server is still mostly idle, it still represents a massive saving of hardware and power, and certainly doesn't equate to virtualisation "not working".
One issue of virtualisation is that not everyone does the same things. One of my clients has four Hetzner servers because they need 4*RAID-1 arrays for the size and performance of their data. They could probably get by with CPU power equivalent to one server, but would really need two servers for the RAM they need. Hetzner has just offered a new server with enough storage and RAM to satisfy my client's needs - but it costs more than the four current servers. Presumably there are other Hetzner customers with lots of CPU use but little disk IO. While CPU utilisation accounts for most variation on power use disk IO also counts for something. Amazon has various offerings for different ratios of IO and compute performance so they can try to match things to use all the resources. If you instruct EC2 to create a high CPU instance it could be run on a system that has mostly low-CPU instances. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/