Cloud versus cloud: A guided tour of Amazon, Google, AppNexus, and GoGrid

Cloud computing offerings differ in depth, breadth, style, and fine print; beneath the heady metaphor lurk familiar pitfalls, complex pricing, and many questions

 

Crashing the cloud metaphor
The legal worries are just part of the details that aren't so certain. One of the biggest dangers is reading too much into the cloud metaphor. While it's largely true that these services are very flexible ways to build up a network of machines, they are far from perfect. What happens if a server or a hard disk crashes in the middle of an operation? Often the same thing that happens when a generic server kicks the bucket: Your data might disappear and then it might not.

An instance of a machine from Amazon's EC2 looks just like a normal machine because after you strip away the hype, it is just another version of Linux running on a chip that probably speaks 8080 machine code and writes data to a spinning platter. If you write something to a good old file in the Unix file system, the cloud metaphor won't protect it. It will stay there until the machine dies. If you shut down the server to save some cash when traffic is low, that's the same thing as dying. That means you can't really scale up and down without a savvy plan for migrating data.

In other words, MySQL in the cloud works just like it does on a generic server. Everything could be lost in a poof unless you start up several instances and mirror them with each other. The magic of the cloud metaphor can't remove this fundamental rule.

If you want something to survive a crash, you've got to put it into the cloud's data stores. These are great services, but they're not cheap. One friend of mine used to back up his disks to Amazon's S3 until he started getting bills for more than $200 a month. He bought a hard disk and kept it on his desk.

The price is higher because the service level is higher. Amazon wants people to be able to trust the data store, and that means providing a level of service that would make a bank happy. Sharing data across servers takes time and careful coding. Google cautions users to be careful writing to its data store because it can be expensive. If you're someone who likes to keep lots of log files just in case, you'll probably pay much more to store them in the cloud than you would in a regular file. Alas, Google doesn't have regular files.

One of the trickier details is trying to understand the prices. GoGrid, for instance, likes to say that its Intel Xeon servers are more powerful than its competitors. Google doesn't even sell server time per se; it just bills you for CPU megacycles, a squirrelly metric. Amazon EC2 has regular-sized machines and bigger ones that are a bit more expensive. When costs change, the companies often lower their prices. But they also raise them when a service turns out to be more expensive to provide than they thought. This complexity will have you scratching your head for a long time because it's hard to know what things will end up costing. That box from Sun may not scale up and down, but the bill isn't going to change with every hit on your Web site.

The Bottom Line

Amazon Elastic Compute Cloud Amazon, amazon.com/ec2

Preview

Cost: 10 cents per hour for a "small instance" (1.7GB of memory, 160GB of instance storage), 15 cents per gigabyte of data storage per month, 10 to 17 cents per gigabyte of data transferred Platforms: Linux-based systems Bottom Line: Amazon EC2 offers a great collection of tools and experimental offerings that is rapidly expanding. Already offering the broadest set of cloud services by far, Amazon supports a wide range of application platforms including JBoss, and active development shows the cloud changing day by day. Cons include endless cutting and pasting for the command-line interface, and the shared storage (S3) is relatively expensive for low-grade data such as log files.

About our Reviews and Scoring Methodology

The Bottom Line

Google App Engine Google, google.com/appengine/

Preview

Cost: About 5 million free page views. After that, 10 to 12 cents per hour of a CPU core, 15 to 18 cents per gigabyte of storage per month, and 9 to 13 cents per gigabyte of data transferred. Platforms: Any Python 2.5 Web application that operates in a sandbox that excludes actions such as writing to the file system. Bottom Line: App Engine makes life easy for programmers who code simple database front ends in Python, though the API is deliberately limited. There are no background threads, files, or other crutches. It's all database, all the time, but only a simplified database at that. The pricing model -- based on squirrelly metrics such as CPU megacycles -- may make costs difficult to anticipate. An application dashboard offers clean views of performance.

About our Reviews and Scoring Methodology

The Bottom Line

GoGrid GoGrid, gogrid.com

Preview

Cost: 12 cents per hour of a CPU core. Load balancing, DNS, 500GB of storage, and incoming data transfers are free. Outbound data transfers cost 25 cents per gigabyte Platforms: CentOS and Red Hat Enterprise Linux with Apache, PHP, MySQL, or Facebook; Windows Server 2003 with IIS, ASP.Net, SQL Server 2005 Bottom Line: GoGrid offers the widest range of machine images, including Windows systems. A clean, AJAX-based control panel makes it simple to get a sophisticated network up quickly and efficiently, and saves you the trouble of cutting and pasting IP addresses and other details. GoGrid doesn't offer many cloudlike features for database storage; you have to mirror the databases yourself. The company is still working on a way to freeze a machine instance so that you don't have to pay for it when it's not running.

About our Reviews and Scoring Methodology

The Bottom Line

AppNexus AppNexus, appnexus.com

Preview

Cost: 22 cents per hour for a 2.83GHz server. High throughput NAS costs 50 cents per gigabyte per month, while archival storage costs significantly lower. Platforms: Linux-based systems Bottom Line: AppNexus is a way to share the cost of owning top-of-the-line enterprise tools. It makes load balancers and file storage systems available on a fractional basis, and it provides a content delivery network that spreads your static files throughout the Web. Cloudlike features are implemented with old-school metaphors like "shared file systems," which may be a good thing if you like the old transparency. The command-line interface is really made for Unix lovers.

About our Reviews and Scoring Methodology