Workload Portability: Ultimate Cloud Edition
January 23, 2009
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I like the PlateSpin range of products a lot, it really does let you take an OS instance + app stack (workload) and move it between different physical machines, hypervisors etc. in a low impact way – if you’ve not come across it before – read this post for more info I see this portability as one of the key infrastructure components if you are looking to build or manage your own internal cloud infrastructures.
This isn’t possible at present, but put your architect hat on and imagine if you could plug PlateSpin Migrate (previously known as PlateSpin PowerConvert) tool into Amazon’s EC2 cloud, or a VMWare vCloud based farm – then you could do whatever you like with your Windows and Linux servers.
By design AWS and vCloud are both supposed to be automatable with web services and APIs to control machine provisioning and control etc. EC2 seems to have all of this now (API docs and example) and vCloud is coming along. (more real details at VMworld I’m guessing).
Moving services between on and off-premise cloud infrastructures is a key concept of vCloud; but I’m guessing this will only be between vCloud based infrastructures, what if you wanted to take advantage of the capacity and scale/commodity pricing from big providers like EC2 (which is Xen based under the hood) to offload some of your internal services – to my mind, there are a couple of scenarios here that PlateSpin could fulfil;
- Disaster Recovery – using the cloud (EC2 or other) for DR capacity; pay per use – use PlateSpin Protect to sync your machine images off to Amazon S3 and have a “panic button” that converts the S3 hosted images to running AMI’s. Brent has a similar idea here around SQL, my proposition takes this to the next level and does it from the OS up; if you did have to move over to the EC2 hosted DR cloud, then you could use it to go back to physical hardware again once you’ve repaired/rebuild your internal infrastructure
- Data centre moves or serious maintenance – use a cloud like EC2 as “swing” capacity to run services whilst you pick up your DC hardware and move it somewhere else (rather than a kit refresh).
- Test & Development; the ability to sandbox new apps in EC2 could be attractive to some organisations where corporate policies hinder or prevent this type of innovation taking place in-house; What if you could do this externally then just bring the machine instances back in-house to put into internal production use (I’ve seen this happening at several customers) – of course IT security teams would probably not be to happy about it.
- Short-term Expansion Capacity; if you experience an occasional surge of demand or load for an internal service. For example; if you have an internal application that you know will get really hit for a promotion or project then you could clone instances of the relevant web/application servers off to EC2 and use some kind of very clever load balancing tech to selectively hand off load to EC2 hosted instances when internal servers start getting saturated – or vice-versa.
Maybe even if PlateSpin were to position their product as a web service itself with downloadable agents – a connector/conversion hub between clouds – now that’s an interesting proposition.
Hopefully this diagram explains some of this idea visually
Issues at present:
- PlateSpin doesn’t have an interface to EC2 (consider this my feature request :))
- There is no secure connectivity back to corp HQ – this is something that as far as I can see AWS has an issue with – out of the box there is no way to have say an IPSec VPN or dedicated private subnet managed and provided by EC2, complicated networking scenarios don’t seem to be possible – you could build your own using software based routers and firewalls on EC2 hosted server instances but this is host based – would be good if EC2 add this sort of service to the platform in future – that would definitely be a killer feature as far as I’m concerned – AWS team, consider this my feature request :))
- VM Persistence is something of an issue with EC2 and I don’t think the EC2 model currently deals with it; with EC2 you pay whilst an instance is running, if you terminate it; i.e switch it off, it’s gone – the data (and that includes OS/app configurations) that you build into the instance are lost. there is no way to archive/suspend/freeze an instance to S3 and “spin it up” as required – I’m guessing this would be feasible for Amazon to build into EC2/S3 – you pay per GB stored on S3 so there is a cost-model for it – again this would be a killer feature for me – there are ways obviously to make your instances “vanilla” and have them auto-install relevant code and data when they are created; examples here and here but that takes a lot of work and isn’t so simple for most corporate type apps.
- You can attach an EBS (Elastic Block Storage) volume to an instance, this is persisted (as long as you keep paying for it) and you can mount it to a single host as a block disk device – but the issue remains with the actual OS instance not being persisted. if its a Windows OS, this is a particular problem as the config is all held in the registry etc. which is part of the OS itself.
- This still doesn’t get you past the concerns/issues over data ownership and cloud security, there is no magic bullet in this respect, just risk management/mitigation.
Anyways. just an idea, feel free to comment and give me your feedback..