On CPU Performance
"On average, Cloud Servers was more than twice as fast as Amazon EC2 at compiling the Linux kernel across all instance sizes."
On Disk I/O
"Disk I/O results show that Cloud Servers consistently have much better write and random write performance than EC2 across most sizes."
They used a combination of IOZone and Linux kernel compiling to conduct their analysis. Here our opinion on this (also commented at the bottom of their article):
Our Comments
We've also compared EC2 and Rackspace performance using geekbench, specjvm, hdparm, mysqlbench and unixbench with one example result set:
Rackspace 4GB Instance:
Geekbench: 2841
hdparm buffered disk reads: 165 MB/sec
SPECjvm Composite result: 51.99
mysqlbench: 1330 wallclock seconds
unixbench: 777
EC2 m1.large instance (w/ EBS local storage):
Geekbench: 3113
hdparm buffered disk reads: 65 MB/sec
SPECjvm Composite result: 36.51
mysqlbench: 1327 wallclock seconds
unixbench: 663
The disk I/O results are a bit better with rackspace based on low level measurements, but at a higher application level like mysqlbench they are very similar. CPU/memory IO performance is also a mixed bag with the EC2 instance performing better with geekbench and Rackspace performing better with unixbench and specjvm.
However, I think it is a bit of a stretch to put Rackspace cloud on the same playing field as EC2. EC2 is a much more mature platform with many many more features like multiple data centers, instance independent storage (ebs), auto scaling and monitoring, load balancing, vpc, and more. Rackspace cloud is basically just VPS with on-demand pricing. Of course they provide free support and an excellent CDN offering based on Limelight (much better than cloudfront), but their IaaS offering leaves a lot to be desired.
Also, on pricing, EC2 is much better on the high end, particular with reserve instances (i.e. an 8GB m1.large reserve instance is $0.17/hr over a 3 year period while an 8GB rackspace instance is 3x as expensive at $0.48/hr). We've also done some public bandwidth testing and all 3 EC2 regions provided generally faster downlink throughput than the Rackspace Cloud Dallas data center.
I think Rackspace is off to a good start with their Slicehost acquired cloud. My hat really goes off to their marketing team too.
Here are links to the geekbench tests we ran:
EC2 m1.large - score: 3113
4GB Rackspace Cloud Server - score 2841
