Comments on Martin Hamilton's blog: Disaster Recovery on a Shoestring

Hi, that's right - I'm oversimplifying a l...

2010-10-02T16:18:56.264+01:00

Hi, that's right - I'm oversimplifying a little.

For a functional setup I think Elastic Block Storage and Elastic Load Balancer would be required.

http://aws.amazon.com/ebs/:
"Volume storage is charged by the amount you allocate until you release it, and is priced at a rate of $0.10 per allocated GB per month Amazon EBS also charges $0.10 per 1 million I/O requests you make to your volume"

http://aws.amazon.com/ec2/faqs/:
"By default, every instance comes with a private IP address and an internet routable public IP address. These addresses are fixed for the life of the instance. These IP addresses should be adequate for many applications where you do not need a long lived internet routable end point. Compute clusters, web crawling, and backend services are all examples of applications that typically do not require Elastic IP addresses."

"In order to help ensure our customers are efficiently using the Elastic IP addresses, we impose the $.01/hr charge for each address when it is not mapped to an instance."

I'll come back to this in a subsequent post!

That's quite right - I intentionally oversimpl...

2010-10-02T08:41:04.005+01:00

That's quite right - I intentionally oversimplified the picture, and the reality would be that you would need Elastic Block Storage (EBS) in addition to an EC2 instance. Blurb from Amazon says... "Volume storage is charged by the amount you allocate until you release it, and is priced at a rate of $0.10 per allocated GB per month Amazon EBS also charges $0.10 per 1 million I/O requests you make to your volume" so $16/month to keep that 160GB stored + transaction related costs. More at http://aws.amazon.com/ebs/

The good news is that I've analyzed the situation a bit more and we only need to maintain 100GB of content :-) The remainder was archived material, old log files etc.

However, my suspicion is that Elastic Load Balancing will also be necessary, as there are some dire warnings in the EC2 bumpf about not relying on persistence of EC2 hosted VM's IP addresses. Costings for ELB are detailed here: http://aws.amazon.com/elasticloadbalancing/

Haven't had a chance to make as much headway on this as I would have liked, as it has taken a while to get my University purchasing card sorted out - but that's done now. Yes, it's all linked back to your credit card number :-)

On the JANET Web Hosting front I believe this is only going to be of very limited use to us, as there is no access to the underlying operating system and the Web control panel for the virtual host would not let us replicate our main Web server config. Bit of a shame, that, but my feeling is that it could still come in handy in a true disaster that knocked out both our primary and secondary sites - or if our fibre links back to the MAN were severed in a way that would take a significant period to repair.

I'll put together another blog post once I have had a chance to experiment with the EC2 stuff...

Hi Martin - great post. Just thinking about your £...

2010-10-01T00:22:44.666+01:00

Hi Martin - great post. Just thinking about your £100 disaster recovery solution though. Surely you would need to maintain the 160GB of data within the cloud as it would not be reasonable to assume that you could quickly (or in fact even at all) upload the website data to Amazon. This would increase this disaster recovery solution by the amount it cost to store 160GB permanently (and presumably bandwidth to keep it updated and a brief server instance - eg for 2-3 hours per day or week - to run the rsync or whatever other sync tool you'd use).