Why can't Amazon AWS migrate a live instance to new hardware when there's a hardware problem?
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I got this message from Amazon (below). Doesn't Amazon have the technology to migrate a running instance from one physical platform to another? I've seen this done at other virtual host providers. Hello, We have noticed that one or more of your instances are running on a host degraded due to hardware failure. i-666XXXXX The host needs to undergo maintenance and will be taken down at 12:00 GMT on 2011-05-13. Your instances will be terminated at this point. The risk of your instances failing is increased at this point. We cannot determine the health of any applications running on the instances. We recommend that you launch replacement instances and start migrating to them. Feel free to terminate the instances with the ec2-terminate-instance API when you are done with them. Sincerely, The Amazon EC2 Team Perhaps they don't want to do a live migration to new hardware when the current hardware is in question--they might move an instance that's in a bad state. But wouldn't it be better to move it and then warn me that the instance may be corrupt?
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Answer:
AWS doesn't support live migration internally as they are not architected to support it. Live migration requires complexity and complexity doesn't scale. AWS has optimized for massive scale and the reduction of their own operational costs, which they are able to pass on to their customers as low prices. Other providers can provide this functionality to you; however, it's typically a manual internal process with high operational overhead. This means there is a good chance these providers will not be competitive long term. It is generally better to assume that all servers, everywhere, fail, and to have backups, DR, and related baked into your deployment.
Randy Bias at Quora Visit the source
Other answers
Most likely because AWS is using a version of the Xen hypervisor that doesn't support live migration, and also because there isn't enough physical bandwidth between servers to support it. This is likely as a cost-saving measure; AWS servers have a single 1G network interface for all network and storage traffic. Fundamentally, AWS believes that you need to design and architect your own app redundancy, and that isn't something they need to do for you.
Mathew Lodge
That is true but to an extent. You have to remember AWS does not get into your data. But what hardware failure are you talking about? One way is just stop and start your instance (keep in my if EIP is not attached Public IP may change) and the host machine foe your instance will change on start. What you can do is, create an AMI of your live instance, launch another instance from that AMI and you have another instance running.
Ranvijay Jamwal
This is less of an issue now that instances are generally EBS-backed. You can simply stop and restart an EBS-backed instance to migrate it from the degraded hardware to to new hardware.
Jarmo Dee
Simple answer is that, EC2 provides other mechanisms to back up and restore your instance. For example, you can move your entire data to an EBS volumes and easily launch another instance. EC2 was not architected to support live migration. They are moving towards it slowly and steadily. It would be done faster if the customers are dying to have that feature.
Anonymous
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