Windows Azure CDN now priced and available!

Last November, Microsoft rolled out Windows Azure Content Delivery Network, allowing you to cache your blobs near your users. It was in free CTP for a while, but starting in July, there will be official support – and a price tag attached.

In a recent post on the Windows Azure team blog, the team laid out the pricing: it’s $0.15/GB in the European and North American data centers and $0.20/GB elsewhere. Additionally, you pay $0.01 per 10,000 transactions. It’s actually exactly what I was guessing at back in November – the same price as Azure data transfer from normal data centers in the Western countries.

There is one gotcha though. The CDN servers are a separate cluster of storage. When a user first requests the file from the CDN, the CDN server also retrieves the data from the Azure storage. This means that for the first hit, you pay for both the Azure –> CDN transport as well as the CDN –> user transport.

For Western countries, the $0.15/GB on both channels makes CDN mostly a convenience feature, providing better performance for users in regions with limited abroad connectivity. However, in the Asia Pacific region where data transfers are priced at $0.45/GB, the CDN can also represent a significant way to cut data transfer costs in the cloud.

In comparison to others

The pricing is reasonably competitive. Amazon CloudFront pushes the price per GB slightly lower when you’re transferring really many GBs of data (hey, these guys have a pricing category for 1000 TB+ of monthly transfer!). The rate per transactions is slightly higher, compensating some of that. However, for most applications, the Amazon implementation is practically just as cheap or expensive as Azure.

Both Amazon and Azure implementations also share the same model regarding origin retrievals; Amazon CloudFront data is stored in Amazon S3, and transfer charges from there to the CloudFront are similar as with the Azure Storage to Azure CDN transfers.

SimpleCDN couples the storage and data transfer to a single package and sells it in bundles. This way, it can show very low calculated costs per GB, but reaching the figures would require knowing the demand in forehand – something that practically never happens. That said, SimpleCDN is rather cheap by any measure; whether its quality of service stands up to the services of the giants is another issue (I don’t have enough experience to judge). At any rate, looking at SimpleCDN’s pricing is enlightening, and their competitive savings examples, while perhaps even more contrived, provide an interesting insight into some pricing issues.

Powering it up

Microsoft’s and Amazon’s key benefit is the ease of use. Since they provide an entire cloud programming platform, your data is somewhat likely to be up there already.

When you want to set up CDN access from an Azure Blob Storage account, just check a “Enable CDN” checkbox and you’re good to go. For optimization purposes, you may also want to tinker with blob caching times to make sure that the CDN is serving up-to-date versions of files, but not refreshing them from the source more often than necessary.

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