Last week Amazon announced the release of Elastic Block Store (EBS), a block based persistent storage mechanism for EC2. This is very exciting news that will make a huge impact on the adoption of cloud computing and virtualisation in general.
I’m not going to go into a huge amount of detail here, if you want to know the full details I suggest you check out the blog entries from RightScale or from Amazon’s own CTO, Werner Vogels ’s blog entry on the subject.
Before EBS, any data you had was lost when you powered down the machine, unless you had backed it to S3. Now with EBS the volumes you mount will be persistent:
Amazon EBS volumes are created in a particular Availability Zone and can be from 1 GB to 1 TB in size. Once a volume is created, it can be attached to any Amazon EC2 instance in the same Availability Zone. Once attached, it will appear as a mounted device similar to any hard drive or other block device.
Although the EBS volumes are quite reliable, to achieve full reliability you should back up your data to S3, and this is done via the mechanism of EBS Snapshots. The interesting feature of these Snapshots is that they are incremental, only the blocks that have changed since the last Snapshot are written to S3.
Currently EBS is priced at a rate of $0.10 per allocated GB per month. They also charge you $0.10 per 1 million I/O requests you make to your volume so you should be careful how you use your volumes.
It should be mentioned that you pay for what you allocate, not what you use, so if you allocate 1TB straight away, even if you don’t use it, you will pay a lot at the end of the month.
What this means for computing
I believe that the release of Elastic Block Storage is going to make a huge impact on IT. Technology Startups and established businesses will now be able to test out their new ideas without having to fork out a lot for expensive equipment. And with the EC2 model you can even shut your instances down at night to further save on costs. We are entering a very exciting time for computing.
If you want to play with EBS, Eric Hammond has written an excellent article describing how to run MySQL on Amazon EC2 with Elastic Block Store.