With I/O being the top bottleneck in modern databases and web applications, a lot of what people call "unpredictable performance" or "virtualization overhead" has mostly to do with sharing (and thin provisioning) storage devices between multiple servers/nodes.
I think there would be a huge market for a performance-oriented VPS provider who could provide each node with its own, dedicated hard drives/SSDs. All major virtualisation tech (KVM/Xen) already supports raw disk mode.
Obviously, space and SATA ports inside servers are an expensive commodity with off-the-shelf hardware, so this project would require at least some custom hardware to offer competitive pricing. I think the tiny mPCIE SSDs sometimes found in laptops would be a good area to explore.
> With I/O being the top bottleneck in modern databases and web applications, a lot of what people call "unpredictable performance" or "virtualization overhead" has mostly to do with sharing (and thin provisioning) storage devices between multiple servers/nodes.
The thing is, most of the problem with sharing a disk simply goes away once you go SSD.
Spinning disk has the characteristic that sequential access is pretty good... and random access is terrible.
If you have two processes both streaming sequentially off the same disk at the same time, if your scheduling algorithm doesn't allow for terrible latency, the disk is going to see random access. This is why spinning disk is so terrible for multi-user setups.
SSD doesn't have that problem. SSD has problems with writes that are not cell-aligned, but this is functionally similar to the problems raid5 has, and much like raid5, it's not a problem when it comes to reads.
EC2 is generally very expensive for CPU. RAM and storage are okay but CPU is crazy.
Anyone know what recommends EC2 over Digital Ocean, Vultr, Linode, etc.? Are they more reliable? Enterprise features? Network bandwidth? Cause right now they look hugely overpriced.
I've hosted on Digital Ocean and Vultr for some time and my uptime is great on both. I run constant ping testing and I do see little glitches from time to time between data centers, but that could be network weather on the global backbone. (I have a geo-distributed architecture so there's stuff running at five different locations.)
You can't look at EC2 as just a place to go for a VM. It's not worth using EC2 unless you either:
A) Already have a lot of other infrastructure on EC2.
B) Want to use the other services offered by AWS.
AWS is a collection of services and APIs that you can compose to build big, complex, scalable things. If you just need a VM host, AWS should be the last place you look.
On the flipside, if you have an application that could benefit from outsourcing some of your infrastructure, AWS could save you time and money. For example, we have AWS managing our DB server (RDS), Load Balancing (ELB), Redis/Memcache servers (ElastiCache), static media storage (S3), DNS (Route53), and some of our CDN capacity (CloudFront). We can manage all of these through the same API client (boto), and the inter-service latency is typically low.
Amazon offers a full ecosystem of services - compute, object storage, CDN, DNS, DbaaS and a lot more - DO and Linode are VPS services with hourly pricing.
I use Linode for production sites. It's easy to create private networks. Performance is better than DO in my testing. I use Digital Ocean for my hobby sites like blog and quick apps since they have inexpensive instances.
EC2 is generally very expensive for CPU. RAM and storage are okay but CPU is crazy.
I'm leaning towards becoming an EC2 apologist on here, but just running quick benchmarks on a t2.micro versus both the $5 and $10 Droplets.
sysbench --test=cpu --cpu-max-prime=40000 run
$5 Droplet ("2.0Ghz", bogomips 4000)- 99.4981s
$10 Droplet ("2.4Ghz", bogomips 4800) - 88.3740s
(I can't find any actual documentation detailing the $10 option being faster, so perhaps this is just random luck on instantiation)
t2.micro ("2.5Ghz", bogomips 5000) - 69.5248s
Now of course the t2.micro won't let you run that around the clock, which for many workloads is entirely fine: as a standard blog host and the like, or the overwhelming majority of server implementations, bursty CPU is exactly what most natural workloads look like.
Of particular relevance is that the Amazon instance (E5-2670) exposes SSE4 and AVX to your VM, which for many workloads could dramatically increase its advantage.
I guess the whole point of this is that the vague CPU terminology that the various cloud vendors use is seldom really comparable. However to your core question, Amazon becomes a value proposition when you are using all of the parts -- S3, load balances, elastic IPs, shared volumes, availability zones, security zones, VPCs, private networks...it is all multipliers to the value of the platform.
As a quick addition on this, the m3.medium -- running on the same processor but governed differently -- takes 160 seconds to run the same benchmark (after repeated runs).
Amazon used to promote their instances via the somewhat comparable ECU metrics. Now, however, unless I'm missing something, you need to try to determine by narrative, because 1 vCPU is very much not equal to 1 vCPU on other instance types.
They still use ECU, but I'm not sure it's comparable across generations of instances, e.g. an m3 with more ECU than an older m1 instance of similar size seems at times to be slower.
The value proposition of these instance types seems to be entirely focused on CPU burst performance, with no local storage, no EBS optimization (though there are provisioned IOPS), and only moderate network performance that is shared.
Relatively poor disk performance is somewhat expected. I'm not sure how fair it is to compare it to instance volumes on other platforms, given the significantly reduced flexibility that brings with it.
