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Comment by sithadmin | Hacker News Reader

>Clueless engineers. The AWS instances don't fail more often or any differently than old school servers.

Instance and host reliability aren't the issue here. The issue is that a disgustingly high number of enterprises rely on vSphere High Availability and Fault-Tolerance features to restart VMs or keep them alive when an OS hangs or the host fails, instead of architecting for high availability at the app layer.

To be entirely fair though, vSphere HA and FT are incredibly friendly to the bottom line relative to rebuilding apps that simply weren't designed for HA.

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My bad. I didn't get that you were talking about the built-in vSphere HA. This thing is truly amazing =)

I thought it was the usual complain about AWS instances dying and needing to be replaced on regular basis. That thing is a myth. An instances can run for years without any issues, if noone stops it manually.

Whether Amazon VMs go for years seems to be a matter of luck in my experience. You need to bake in HA for any service you really depend on either by having copies or ability to start new ones at will.

> An instances can run for years without any issues, if noone stops it manually.

Sometimes.

And sometimes the hardware it was running on dies or there was a maintenance event. Now you have a message like this waiting for you:

http://stackoverflow.com/questions/34259924/instance-retirem...

Fail to notice? Bye bye instance.

That said, you're right, it's not any more common than hardware failure. But that's common enough. Keep a backup and don't expect your stuff to always be there no matter what.

You can also do that in AWS using CloudWatch Auto Recovery functionality. Of course it's still better to design for HA, but if it's not possible Auto Recovery should be able to add a bit of resiliency.

vSphere HA and FT should work in AWS so those people should be happy.

> High Availability and Fault-Tolerance features to restart VMs or keep them alive when an OS hangs or the host fails

"High Availability and Fault-Tolerance" would hopefully involve more than restarting the VM.

I mean, you have like bajillion people that solved the above "challenge" with a three-line bash script. And not one of those people would call it "High Availability and Fault Tolerance". It's just a small shell script.

vSphere HA indeed restarts the VM on a different host with its storage, network, etc. intact. This is so trivial that EC2 didn't offer it for years.

vSphere FT replicates a VM while it runs so that it doesn't even notice the failure of one of the underlying servers.

> vSphere HA indeed restarts the VM on a different host with its storage, network, etc. intact. This is so trivial that EC2 didn't offer it for years.

How often is your hardware fucked up enough that you need to move to another machine?

Honestly, if that happens often, there is something wrong with your hardware or your hardware provider or something.

On a 900-servers fleet on AWS, yeah, sometimes it would warn me that "the server needs to be retired" or whatever. Then I stop the server, then start it. Sure, inconvenient, but happens maybe... once a month? In fact, the frequency is decreasing so maybe once every two months?

> vSphere FT replicates a VM while it runs so that it doesn't even notice the failure of one of the underlying servers.

That would be great, right? You paid some $ to VMWare and now your servers never go down?

Excuse me but, that did not happen.

Enterprise data centers are probably much less reliable than AWS. My take on HA & DR in general is that it's the kind of thing that you might use once in your career but it's probably worth it since it saves you from being fired.

I have to agree with that. Yeah, where I work, we spend a huge amount of time making sure that we are ready for something.. that may never happen.

Makes you think.

Thanks.

"How often is your hardware fucked up enough that you need to move to another machine?"

VMware HA runs quite a bit IME for a variety of reasons (network failure, storage issues, etc). "The network is reliable" is a classic fallacy of distributed computing.

More often used is Vmotion and DRS which transparently moves VMs around physical hosts at runtime with no downtime and very minimal performance hit . Servers, switches, and fabrics need maintenance, firmware upgrades, hypervisor OS patches, etc. in most data centers.

"That would be great, right? You paid some $ to VMWare and now your servers never go down? Excuse me but, that did not happen."

VMware FT is used in almost every major company on the planet that runs virtualized database instances that can't go down. It is serious technology.

AWS has mopped up the IT industry to date, and this is them going hard after Microsoft which is making inroads.

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