As I said, rolling your own will not give you a guarantee, it will just give you the responsibility for failure. We don't offer the guarantee, because we don't want you to believe it can't fail.
Last time I had a failed storage controller, HP delivered a replacement in four hours. Last time a service provider went down, I had no visibility into the repair process, and had to explain there was nothing I could do... For five days.
It seems like you've outright admitted you can't guarantee what they need, yet you still urge them not to leave your business model. Maybe come back when your business model can meet their needs.
That may sound like cold comfort on the face of it, but it's key to getting the most out of cloud and exceed the possibilities of an on-prem architecture. Rule #1 is, everything fails. The key advantage to a good cloud provider (and there are many) is not that they can deliver a guarantee against failure (as boulos stated correctly) but that they'll allow you to design for failure. The issue becomes when the architecture in the cloud resembles that which was on-premise. While there's still some advantages, they're markedly fewer, and as you said, there's nothing you can do to prioritize your fix.
They key to having a good cloud deployment is effectively utilizing the features that eliminate single points of failure so that the same storage controller failure that might knock you out in your on-prem can't knock you out in the cloud, even though the repair time for the latter might be longer. That brings its own challenges, but brings huge advantages when it comes together.
Disclosure: I work for AWS.
As someone else alluded to downthread: anyone claiming they can provide guaranteed throughput and latency on networked block devices at arbitrary percentiles in the face of hardware failure is misleading you. I don't disagree that you might feel better and have more visibility into what's going on when it's your own hardware, but it's an apples and oranges comparison.
Back when I worked in enterprise services, it was a requirement that we had good support contracts — 1-, 4- or 8-hour turnarounds were standard.
If you're running a serious business, support contracts are a must.
Manufacturer specifically asks customer to keep it informed where the equipment is physically located, and then prepositions spares to appropriate depots in order to meet the contractual requirement established when the customer paid them often a large amount of money for 4-hour Same Day (24x7x365) coverage for that device.
This isn't how hyperscale folks operate for the same reason Fortune 100's rarely take out anything more than third-party coverage when their employees rent vehicles, it becomes an actuarial decision, the # of 'Advance Replacement' warranty contracts and the $ involved, vs. buying a % of spares and keeping those in the datacenter then RMA'ing the defective component for refund/replace (on a 3-5 week turnaround time).
tl;dr - Operating 100-500 servers you should likely pay Dell and they'll ship you the spare and a technician to install it, operating >500 servers and you should do the sums and make the best decision for your business, operating >5000 servers and you probably want to just 'cold spare' and replace yourself.
Now, these contracts aren't like your average SaaS offering. We had a sales rep and the terms of the support contract were personalized to our needs. I imagine some locations were offered better terms for 4 hour service than others.
As I learned long ago, never say no to a customer request. Just provide a quote high enough to make it worthwhile.
That said I suspect most enterprises pay too much; as in their money might be better spent buying triple mirroring on a JBOD rather than a platinum service contract with a fancy all in one high end RAID-y machine.
Get servers from Quanta, Wistron or Supermicro, and switches from Quanta, Edge-core or Supermicro. The $$$ you save vs a name-brand OEM more than pays for the spares. Use PXE/ONIE and an automation tool like Ansible or Puppet to manage the servers and switches, and you can get a replacement server or switch up and in service in minutes, not hours.
If you're moving out of the cloud to your own infrastructure, it makes sense to build and run similarly to how those cloud providers do.
There's non-trivial cost involved in simply being staffed to accommodate the model you propose, all of the ODM's have some "sharp edges" and you need to be prepared to invest engineering effort into RFP/RFQ processes, tooling and dealing with firmware glitches, etc.
Remember that 500-rack (per buy) scale is table stakes for "those cloud providers", it is their business, whereas GitLab is a software company. Play to your strengths.
I am shockingly biased (I co-founded Cumulus Networks) but working with a software vendor who can help you with the entire solution is very helpful.
The scale gitlab has talked about in this thread is firmly in the range where self-sparing/ODM/disaggregation make sense. I think 500 racks is a huge overestimate, I think the cross-over point is closer to 5 racks.
> had to explain there was nothing I could do... For five days
The good alternative would be that you controlled the infrastructure and it didn't break. The bad alternative is you directly control infrastructure, it breaks, and then you get fired.
It's untrue that "the cloud" is always the right way. When you're on a multi-tenant system, you will never be the top priority. When you build your own, you are.
Google and AWS have vested interests (~30% margins) in getting you into the cloud. Always do the math to see if it's cost effective comparatively speaking.
Transparency from GitLab is excellent but you shouldn't really generalise statements about cloud suitability without the full picture or "Walking a mile in their shoes".
> Providers don't provide a minimum IOPS, so they can just drop you.
The reason I ask is because the blog post generalizes a lot about what cloud providers offer or what the cloud is capable of, but doesn't explore some of the options available to address those concerns, like provisioned IOPS with EBS, dedicated instances with EC2, provisioned throughput with DynamoDB, and so on.
You're right that the blog post was generalizing.
BTW We looked into AWS but didn't want to use an AWS only solution because of maximum size, costs, and the reusability of the solution.
So, RAID multiple EBS volumes and you have a larger disk.
New job title: Networked Infrastructure Actuary
Recently I bought an old SuperMicro server on eBay, configured it with 2 6-way AMD Opterons, 3 8-way SATA controllers, and 32GB of memory. With 4TB 5700RPM drives in an 8-way software RAID6, it could do 800MB/sec. I realize it's not small file random I/O, but a blended configuration where you put small files on SSD and large files on spinning disk would probably be pretty sweet.
My intuition is that learning all the ins-and-outs of AWS, and how to react and handle all kinds of situations, is not that much easier than learning how to react with your own hardware when problems come up. Especially consider that AWS is constantly changing things and it's out of your control, whereas with your own hardware, you get to decide when things change.
If you can colocate physically close, it's a lot easier. Our colocation was in Fremont but our office was in San Fran, so it was a haul if we had to install or upgrade equipment. But even so, there was only 1 or 2 times in 7 years that we needed to spend 2 consecutive days at the colo. One of those was during a major upgrade where it turned out that the (cheap) hardware we bought was faulty.
When you run your own hardware you have all the engineering you were already doing plus investing to upkeep and to improve your architecture.
As Google's boulos said, that's where the real costs are.
In an earlier comment you said EBS only goes to 16TB and that is "an order of magnitude less" than your requirement, however, thats per volume, you can attach many volumes in much the same way as servers have many disks.
Scale horizontally not vertically, add more OSD instances? With each you can attach a number of EBS or PD volumes which each IOPS characteristics that in aggregate are sufficient to service your workload?
If you want to avoid EBS or PD entirely, is there a reason you can't look at 'i2' or 'd2' instance types?
https://cloud.google.com/compute/docs/disks/performance https://aws.amazon.com/ebs/details/#VolumeTypes
At a fundamental level you're just moving the problem and trading managing metal (which is hard) for I/O guarantees.
"Why is this harder than you might expect?" - you stated elsewhere that you'll have Remote Hands do rack/stack. Providers like Equinix refer to this as "Smart Hands". Everyone who's managed a reasonable-sized environment finds this term highly ironic, as the technician can and will replace the wrong drive, pull the wrong cable, etc.
I've done an non-trivial amount of infrastructure 'stuff' (design, procurement, install, maintenance, migration) for some well-known companies, if you want to Hangout for an hour and pick my brain, gratis, my e-mail is in my profile.
There is no guarantee of SLA in any distributed system. The best you can do is measure things and know what you'll get most of the time.
If you want SLA, you can make a single server with 10TB of memory as storage. That's solid choice! :D
The OP is asking for guaranteed IOPS/latency SLA for which they're willing to pay HUGE money for by ROLLING THEIR OWN.
Possibly think about high service pricing tiers for systems that require it. This is a standard operations problem that can co-exist within pooled service models.