How are you expecting the automatic failure to work? Even with shared storage, you have to be extremely careful or else its pretty easy to corrupt the guests file system.
If thereās a shared NAS / SAN connected to 2x CloudMin servers, then the Cloudmin servers could very easily do automatic fail over without any service interruptions.
My suggestion:
Let the CloudMin sync the config files between the 2 servers, then run a watchdog or Linux HA script to check and see if the active server goes down, then start-up the instance on the other server. This wonāt give 100% uptime though since most VPSās will take a minute or 2 to boot-up.
But, how does other companies do this? Maybe my suggestion isnāt the best, there could be other options which are better.
They donāt! Very few cloud computing products offer automatic failoverā¦because it is a problem that pretty much always requires participation of your applications, in order to avoid data loss.
Iām pretty sure failover of virtual machines is not coming in 4.4 or 4.5. Thatās a huge bunch of problems to be solved.
Jamie may have been speaking of failover of the Cloudmin management server, which we recently discussed, and this one is much more addressable by us, because the application in question that has to protect data is ours. Since we canāt control your applications, failing over for your apps will never be something we can fully automate (though we can provide tools to make it easier, and we will).
Vmwareās solution to this is called VMotion. Two host servers connected to san running at the same time.
Resources are dynamically allocated between the two hosts. When an outage occurs, the virtual instances (hosts) are transfered to the other functioning server seamlessly.
VMotion is used for other things as well, such as server maintenance. Admins can now perform hardware upgrades and maintenance durring the day without effect to the end users.
VMware did a really cool demonstration video on this showing an end user playing solitare on a virtual desktop while being āvmotionedā to another host. Seamless. (okay, so it was solitare, maybe not THAT coolā¦)
Citrix XenServer offers the same functions within their HA Enterprise version of XenServer.