ENKI versus Rackspace Cloud sites

Can you compare RackSpace Cloud Sites to ENKI's Services, especially considering that they're both managed?

I will attempt to compare them on some of the factors that differentiate them the most.

1. Market. Cloud Sites is aimed at replacing bulk hosting which suffers from severe usage constraints but is perfect for small websites because of its low cost. Cloud Sites takes the next step and adds scalability and the option of Windows or Linux. Both traditional bulk hosting and Cloud Sites offer management in the sense of routine system administration tasks, but leave ultimate responsibility for your website's administration to you. ENKI PrimaCloud is targeted at high volume, professional sites where performance requirements dictate more than simple load-based scaling and uptime is critical. This would typically be a dynamic site with custom or open-source software, often which requires software release processes that minimize downtime. With our optional operations services we can completely relieve you of any technical responsibility for managing your live site.
2. Support/Operations Services. Rackspace takes responsibility only for generic, routine system administration. ENKI's optional Operations-as-a-Service plans can completely eliminate the need for you to have a system administrator, 24x7 support staffing, or even database administrators. What if the PHP upgrade breaks your application? Rackspace can't help. Or, what if your site is slow due to a unoptimized database query? Again, they don't offer that service. Many of our customers outsource their programming to a software house and their IT to us, only keeping sales, customer service, and finance in house. However, if you want to be your own system administrator, we will simply provide a highly reliable virtual private datacenter (with one or more servers) for you to set up your application in, which comes with basic support to assist you in making the most of our environment. One other difference is that while we both offer 24x7 support, ENKI guarantees our response time to ticket submissions and publishes our support metrics, which is essential to business customers.
3. Price. Rackspace prices their service at $149 to compete with bulk hosting, which they are trying to take business away from. However, they have steep overage rates that make large deployments get expensive fast. And, they don't define what a "cycle" is so it's hard to estimate what your deployment will cost. ENKI charges per CPU-hour, disk GB-hour, and GB transferred. Instead of charging you more for overages, we avoid a package (except in the package plans on our website at http://shop.enkiconsulting.net) and instead offer volume discounts so your disk, transfer, and CPU prices go down as you use more. In the case of CPU usage 1GB and 1/4 core is $112/mo, and that can drop to 50% off as soon as you reach 8GB/2 cores, and drop even further as you use more. Storage is priced at $0.20/GB and drops as you use more. Bandwidth is priced at $0.17/GB and drops with volume. Because we deal in familiar units, if you can run your application now and measure its resource usage, you'll know what you'll be paying with our service. For example, one of our customers who serves educational videos has 25TB of video stored with us, which would cost $9000 more per month at RackSpace. If you're curious what your deployment would cost with ENKI, we're happy to quote any resource requirements you may have. Based on their quoted pricing, I'm guessing that RackSpace's service is a better deal for very small sites or ones that don't scale up often, whereas ENKI's services are a better deal if you expect a lot of traffic or large peaks, or use a lot of bandwidth or storage.
4. Scaling. While Rackspace's scaling may work well for many applications, we have discovered that our average customer who needs scaling is not, well, average. Some need to scale based on CPU load, others on database load, others on HTTP transaction time. With our operations services, or your technical expert, you can build exactly the type of scaling and load balancing that best serves your application. Rackspace doesn't say how large your application can scale to. Depending on the time of day, most cloud providers actually run out of non-reserved resources, which can put a damper on your application right when you need it most. I recently took a class from a vendor of ours that used Amazon's AWS for the lab computers. The class had to be cancelled because they couldn't get enough instances out of Amazon! We solve this problem by allowing you to reserve computing power at a very low price, and pay us the remainder when you actually use it.
5. Technology. Rackspace doesn't tell you what kind of servers, storage, or interconnect technology they use, so you can't really tell what you're getting compared to, say, the computer under your desk. ENKI publishes the details of its architecture on our website, which is highlighted by powerful 2.8GHZ Opterons (Intel optional), 80Gbit/sec Infiniband interconnect, Sun Open Storage SAN arrays with RAID 5 on many spindles and optional SSD storage acceleration, and completely dual-redundant interconnect, switches, firewalls, routers, and internet connections for the highest levels of reliability. We also base our virtualization on VMWare, which means you get secure virtual machines that function just like real servers WITH a shell login, except they can be scaled up or down easily. Our delivery model is a virtual private data center, not Rackspace's vague platform-as-a-service in which you may not be able to find log files or diagnose performance problems.
6. Reliability. I couldn't find a statement on the reliability of Cloud Sites. ENKI guarantees that your virtual private data center will be up 99.975% of the time, and we back it up with a 10x refund if we don't meet our promise, so you know we're working hard to keep your site up. If you choose to use our operations services to manage your site, we can also guarantee uptime for your *application* - something nobody else offers. The actual guarantee depends on the software you're running.

Which is right for you? Our experience is that if cost of computation is your primary consideration and your overall compute load is small, other services such as RackSpace's are your best bet since they offer great introductory packages. On the other hand if uptime, scalability, and the ability to use your virtual data center to get the same results as you would get from building your own are important, ENKI is a very good choice. Our founder, Dave Durkee, built the million-customer datacenter for NetSuite and our manafement team's experience in running such a reliable 24x7 service is built into our offerings. This is why SaaS service websites like Kashoo and Contact Science have chosen us. If you are planning to deploy a Software-as-a-Service offering with true 24x7 availability, then our operations services can save you the cost of hiring administrators and a 24x7 response staff, which will make our services more cost-effective than any cloud or hosting solution.