@scottalanmiller said in New Infrastructure to Replace Scale Cluster:
That might be a way to achieve HA, but it isn't the definition of it. The definition of it comes from the level of availability, nothing to do with the mechanisms or attempts at it. You are correct that people often confuse HA (a level of availability) with FT (a physical type of protection whose purpose is to help provide HA, or at least "better A".)
No, FT is about zero service interruptions, you're basically running multiple copies of the same service in either standby or load-balanced manner, and if one of a few (depends on the SLA) service instances go down, overall service availability is not harmed. With HA, the service availability is higher than with none, but it's not meant to be zero downtime in case of failure. All HA does is monitor the service and use technical means of making sure it stays up as much as possible, by failing the service over to another resource (a DR site, a standby host, a DC on Mars - doesn't matter).
With today's advent of distributed services, FT is what is usually being run, since it does make more sense, but HA is still used for the bulkier services, like VMs or large service nodes (e.g. openstack controllers)
But it is also incredibly true. You can't "just buy" HA, doesn't work. No product anywhere can do HA if you don't treat it properly or make the things around it support HA as well. It doesn't require "inventing anything", it's just obvious common sense.
I don't see it that way. If you want HA for a service, you pay for a solution to make it HA, that includes all the components that will protect it from various types of failure as well as provide SBA (several layers of SBA if you have the money). But in the end, it all translates to dollars. You level of paranoia (or the list of stuff you want to protect the service from) vs your budget.
Sure, but that is 1) almost always untrue, very few vendors actually do anything to achieve HA 2) when they do, they are becoming the IT department and building, not buying, HA.
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All the vendors dealing with IT infrastructure have tons of HA oriented solutions. From hardware vendors selling RAID controllers, power management devices and redundant PSUs, to software vendors building support for HA into their products. I find it hard to think of any IT product I've used recently that didn't have HA or FT built in.
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That doesn't make any sense.
See, this is where it all falls apart. Your example proves our point. In your example with the IPOD, you aren't even trying to make HA. oVirt's HA option is actually terrible here because it tricks the humans into thinking there is protection where there is not and makes people often (where makes = allows their brains to accept) introduce more risk, lowing their availability below standard, by seeing the term HA applies to one isolated layer of the stack and ignoring the increased risk of the overall stack.
No, the solution provides protection against a hypervisor failure. You also want to protect against switch failure - buy another switch, you also want to protect against storage failure - make the storage HA. oVirt isn't a networking or storage platform, it uses storage and networking. What oVirt does do is run VMs and control hypervisors. So if a VM dies or a hypervisor dies - oVirt will provide the HA. If all you have are three hosts, what I advised on isn't the safest solution, but it is the easiest to build and run, as well as expand upon later, when budget is available for covering the SPOFs in the setup. It will also provide better performance than using gluster, and there might be more advantages in terms of disk space availability, depending on the hardware the OP has.
I'm not arguing it is safer this way, I'm saying it is easier to build and reasonably safe if backups are done, especially if there is more budget to come in later in the game. Something to get started with.
The user has to be aware of the SPOFs in the system, I'm not saying there are none. The user also has to work at eliminating them, but again, you're applying the logic of a large company with large resources to a tiny little shop with 3 machines. At this level, they might as well just run everything locally on 3 disparate hosts and be done, that's even easier. The point of oVirt here is to start a proper virtual DC from some small set of available boxes and grow it into a proper solution. Nothing involving 3 hosts and a switch can provide real HA in any case.
So please stop running away into depths that are irrelevant to this particular setup. We already know you're an IT bigshot, there's no need to keep showing off.
Integrator is industry speak for the vendor advocate. When anyone in IT says vendor, they mean integrator. It's just accepted that they are the channel arm for their vendors and to the IT side they are one and the same. Both are vendor advocates, both are sales people, one just repeats the marketing of the other.
Sure, but that integrator will do everything for you - networking, HVAC, servers, storage, software - all designed and built as per your requirements, as one single product - you DC.
The marketing trick ...
So much text with nothing actually said. That's actually a marketing trick. Or a politician's trick, whatever.
When you deal with an integrator/vendor/consultant/etc you go over the proposed solution, and it is up to you to see where you're being oversold on stuff and where the proposed parts of the system are actually needed. If you haven't done your due diligence - it's your fault and you should leave the profession, instead of blaming "marketing tricks". All this talk of marketing tricks is basically an attempt at shifting the blame at not having done proper due diligence when signing the purchase contract, nothing more.
When I did freelance DC design, I always pointed out the specific points which could be an SPOF and agreed with the customer on whether they want and can afford to address them or not, instead of just trying to milk them for money. That usually got my overall solution prices to be much lower than what large vendors and integrators offered. I ended up making less money, but having loyal customers who trusted me and kept coming back. If I just came in and started pushing a small enterprise into building wall street level solutions, I'd have been kicked out of the building. But when the solution was up, with known, budget related issues, we always had a plan for the next few years to address these issues, as well as a backup plan to protect the really important aspects of the business. In a few years, gradually, the issues got addressed and the setup grew more reliable, as budget permitted. Had I come in demanding everything was covered from the start, there wouldn't have been any setup to grow and improve in the first place.
Again, I'm not saying there is perfect HA in the solution, I'm not saying it's totally reliable. I'm saying it's a start with some protection against known failures, and a set of SPOFs to be aware of and address in the future. I'm not trying to sell any false promises. For a small business with 3 servers, this is as much as they can hope for anyway.
If you eliminate the storage SPOF, you still have a network SPOF in place, and you're running a badly performing storage system, driving the amount of network traffic up as well as tripling the storage consumption. And you're adding a lot more software into the mix, software that can break, have bugs etc etc etc. All of that without actually having the perfect HA - there's no redundant networking, no redundant HVAC and no DR site. OMG, we're all gonna die!
