FreeBSD/EC2 on C5 instances
daemonology.net
daemonology.net
To name a few:
1. EBS volumes attached to C5 instances show completely bogus CloudWatch metrics, over an order of magnitude higher than reality (e.g. average read/write latency prints at 100-60,000ms depending on load)
2. C5 instances don't work - at all - behind an NLB with a Target Group pointing to it as an "instance". You have to put it in "IP" mode.
3. OpsWorks, as always, lags way behind AWS offerings. You can't launch C5 instances. This was true of even R4 instances for a while, but you could at least change them via API. Not so with the C5 instances; unless you want to lose track of their type completely, you just have to abstain for now.
3a. As a result, we have to run R4 instances for some of our web tier - despite not needing the memory - because they have the highest network allocation. To make matters worse, AWS won't tell you the network allocation. You don't know until you start dropping packets.
4. ZFS on C5 instances can behave strangely. We've been unable to resize drives (zpool online -e <pool> <drive>) if they're identified by ID ("unable to read disk capacity"). Moving the instance back to any other type fixes the issue.
As always, you expect a couple of quirks with a new architecture, but I found myself wishing they had just stuck a new board with a Skylake chip into a rack and launched it.
Compared to this, GCE has a far more attractive offering: even ignoring all these issues, we simply can't get the instance size we want (a few fast CPUs + lots of memory). It just doesn't exist.
What sort of work do you have that requires the latest generation ? Or more why do you want the latest ?
Id expect aws to always be behind the ball - are they the right platform for you?
Gce is interesting, im moving half of my infra over there - but again its not really about their hardware offerings. Its more about being multi cloud/redundant
AWS is indeed behind the curve more often than not, but they also have some amazing hosted products. That was a bigger deal in 2014 than it is now (Kubernetes will eat the world) but it's still a reliable offering, and reliability is our most important criteria.
Agreed re: being multi-cloud in the end. It's the only responsible choice above a certain scale.
I don't know what you mean by 'late'. Skylake Xeons were delayed and have only been released recently, at least partially. You may be able to get them from vendors like Dell but you still can't go out and buy one anywhere that I'm aware of.
Ugh, I hate that. They also have hidden limits on the number of incoming tcp connections you can have.
Do you have proof of this?
We had a very excited account rep because of where I work, but he was only barely able to confirm the limits were there, he wasn't able to get them raised or removed, nor could he tell us the limits by machine type.
There's a thread from 18 months ago on the aws forums [1], where an aws rep more or less confirms, but again provides no information
[1] https://forums.aws.amazon.com/thread.jspa?threadID=231806
I wouldn't be surprised if you're hitting an edge case with the tighter integration* between NLB's and instance associations. If you haven't already, please do reach out to support.
* from the docs "If you specify targets using an instance ID, the source IP addresses of the clients are preserved and provided to your applications. If you specify targets by IP address, the source IP addresses are the private IP addresses of the load balancer nodes."
We're also continuing to investigate the reported latency in the console. Because this is a derived metric from VolumeTotal{Read,Write}Time and Volume{Read,Write}Ops, there may be a miscalculation happening due to the change in dimensions.
It seems more likely that they've put in a software device model of NVME as a replacement for the BlkBack software device model that the BlkFront driver talked to. Not much different than the software e1000 NIC that xen/qemu already supports.
That said, with their virtualizable Annapurna wonder-NIC, they could be doing it in "hardware", though even in that case a reasonable part of the device model would be software, just running on a NPU, not a CPU.
Hopefully Amazon will disclose more details.
Now, exactly what form that hardware takes is an open question. I would assume it's something like "NVME interface hardware" + "ARM CPU which implements the EBS protocol" + "25 GbE PHY", but that guess is based solely on "that's how I would design it".
> There's absolutely no way that they would get the performance I'm seeing from an emulated disk. We're talking to real hardware, exposed via PCI passthrough.
There's a wide spectrum between "emulated" and "real hardware, exposed via PCI passthrough". Passing through to PCI hardware, in and of itself, gains you very little in terms of absolute guest-visible performance versus eliding all VMEXITs via other means, but it has other important characteristics that I suspect AWS very much wants in the c5 family.
> I would assume it's something like "NVME interface hardware" + "ARM CPU which implements the EBS protocol" + "25 GbE PHY", but that guess is based solely on "that's how I would design it".
I would expect something along these lines, although I'd be a little surprised if they bothered putting the NVMe bits down in silicon. My personal guess would be a good silicon DMA engine and PCIe interface married to sufficient general-purpose processing (ARM SoC, FPGA, etc.) to keep pace with the NVMe Command/Completion queues.
Regardless of how they've implemented it, the end-to-end result seems to hang together very nicely. Kudos to the team at AWS.
(note: I work on Google Compute Engine's hypervisor; my speculation about AWS really is speculation about how they'd do this — the two companies have very different engineering approaches, so I may be entirely wrong trying to project onto theirs — like I said at the top, it's fun to try :)
You and Colin both know they bought Annapurna Labs, right?
We don't have to speculate _that_ much about what is probably going on here...
I guessed a hardware NVMe interface because that seems like something which could be acquired more or less off-the-shelf, thus minimizing the engineering risks.
(Colin's speculation in a peer reply is also reasonable -- personally I've seen enough errata in "off the shelf" IP to shudder at the idea of anything in silicon that doesn't have to be, but fundamentally I'm a SWE, so that would be my take, wouldn't it)
Honestly, I'm mostly curious about how much of "KVM" you're running that's stock, how much is modified, and how much of the userland is running on the far side of PCIe rather than in host ring3 (particularly given "C5 instances are built using a new light-weight hypervisor, which provides practically all of the compute and memory resources to customers’ instances.").
[0]: Especially this one: https://news.ycombinator.com/item?id=15641391
"but the latest generation EC2 instances offload networking and storage processing to hardware. This is the case for both for instances that use Xen and C5 that uses the new KVM-based hypervisor."
So that seems to confirm an offload to hardware for storage.
1) You don't have to pass PCIe through to hardware to get performance that makes it look like you have.
2) We know they're offloading though, so here's what I think it looks like.
We will have some more details on how this all works at re:Invent in a couple weeks.
Looking forward to the upcoming 11.2 AMIs :)
Speaking from my (limited) project management experience, I found distributing tasks to the right person is actually a talent in itself.
Note: I was actually surprise how many people could not do it when I was trying to transition away into another project.
it's been a while since i've had access to nvme gear but it "just worked" at the time - although my use case was for a a daemon that accessed the block device directly to do its own horrible things to it.