First stab at addressing per-second billing (#519)

* First stab at addressing per-second billing

* Fixed dead link.

README.md

@@ -789,7 +789,7 @@ EC2
 -	📒 [Homepage](https://aws.amazon.com/ec2/) ∙ [Documentation](https://aws.amazon.com/documentation/ec2/) ∙ [FAQ](https://aws.amazon.com/ec2/faqs/) ∙ [Pricing](https://aws.amazon.com/ec2/pricing/) (see also [ec2instances.info](http://www.ec2instances.info/)\)
 -	**EC2** (Elastic Compute Cloud) is AWS’ offering of the most fundamental piece of cloud computing: A [virtual private server](https://en.wikipedia.org/wiki/Virtual_private_server). These “instances” can run [most Linux, BSD, and Windows operating systems](https://aws.amazon.com/ec2/faqs/#What_operating_system_environments_are_supported). Internally, they use [Xen](https://en.wikipedia.org/wiki/Xen) virtualization.
 -	The term “EC2” is sometimes used to refer to the servers themselves, but technically refers more broadly to a whole collection of supporting services, too, like load balancing (CLBs/ALBs), IP addresses (EIPs), bootable images (AMIs), security groups, and network drives (EBS) (which we discuss individually in this guide).
--	💸**[EC2 pricing](https://aws.amazon.com/ec2/pricing/)** and **[cost management](#ec2-cost-management)** is a complicated topic. It can range from free (on the [AWS free tier](https://aws.amazon.com/free/)) to a lot, depending on your usage. Pricing is by instance type, by hour and changes depending on AWS region and whether you are purchasing your instances [On-Demand](https://aws.amazon.com/ec2/pricing/on-demand/), on the [Spot market](https://aws.amazon.com/ec2/spot/) or pre-purchasing ([Reserved Instances](https://aws.amazon.com/ec2/pricing/reserved-instances/)).
+-	💸**[EC2 pricing](https://aws.amazon.com/ec2/pricing/)** and **[cost management](#ec2-cost-management)** is a complicated topic. It can range from free (on the [AWS free tier](https://aws.amazon.com/free/)) to a lot, depending on your usage. Pricing is by instance type, by second or hour, and changes depending on AWS region and whether you are purchasing your instances [On-Demand](https://aws.amazon.com/ec2/pricing/on-demand/), on the [Spot market](https://aws.amazon.com/ec2/spot/) or pre-purchasing ([Reserved Instances](https://aws.amazon.com/ec2/pricing/reserved-instances/)).
 - **Network Performance:** For some instance types, AWS uses general terms like Low, Medium, and High to refer to network performance. Users have done [benchmarking](http://stackoverflow.com/questions/18507405/ec2-instance-typess-exact-network-performance) to provide expectations for what these terms can mean.
 
 ### EC2 Alternatives and Lock-In
@@ -806,7 +806,7 @@ EC2
 	-	Selecting instance types is complex since there are so many types. Additionally there are different generations, released [over the years](https://aws.amazon.com/blogs/aws/ec2-instance-history/).
 	-	🔹Use the list at [**ec2instances.info**](http://www.ec2instances.info/) to review costs and features. [Amazon’s own list](https://aws.amazon.com/ec2/instance-types/) of instance types is hard to use, and doesn’t list features and price together, which makes it doubly difficult.
 	-	Prices vary a lot, so use [**ec2instances.info**](http://www.ec2instances.info/) to determine the set of machines that meet your needs and [**ec2price.com**](http://ec2price.com/) to find the cheapest type in the region you’re working in. Depending on the timing and region, it might be much cheaper to rent an instance with *more* memory or CPU than the bare minimum.
-  - **Turn off** your instances when they aren’t in use. For many situations such as testing or staging resources, you may not need your instances on 24/7, and you won’t need to pay EC2 hourly costs when they are suspended. Given that costs are calculated based on hourly usage, this is a simple mechanism for cost savings. This can be achieved using [Lambda and CloudWatch](https://aws.amazon.com/premiumsupport/knowledge-center/start-stop-lambda-cloudwatch/), an open source solution like [Scalr](https://github.com/Scalr/scalr) or a SaaS provider like [GorillaStack](https://www.gorillastack.com). (Note: if you turn off instances with an ephemeral root volume, any state will be lost when the instance is turned off. Therefore, for stateful applications it is safer to turn off EBS backed instances).
+  - **Turn off** your instances when they aren’t in use. For many situations such as testing or staging resources, you may not need your instances on 24/7, and you won’t need to pay EC2 running costs when they are suspended. Given that costs are calculated based on usage, this is a simple mechanism for cost savings. This can be achieved using [Lambda and CloudWatch](https://aws.amazon.com/premiumsupport/knowledge-center/start-stop-lambda-cloudwatch/), an open source solution like [Scalr](https://github.com/Scalr/installer-ng) or a SaaS provider like [GorillaStack](https://www.gorillastack.com). (Note: if you turn off instances with an ephemeral root volume, any state will be lost when the instance is turned off. Therefore, for stateful applications it is safer to turn off EBS backed instances).
 -	[**Dedicated instances**](https://aws.amazon.com/ec2/purchasing-options/dedicated-instances/) and [**dedicated hosts**](https://aws.amazon.com/ec2/dedicated-hosts/) are assigned hardware, instead of usual virtual instances. They are more expensive than virtual instances but [can be preferable](https://aws.amazon.com/ec2/dedicated-hosts/) for performance, compliance, financial modeling, or licensing reasons.
 -	**32 bit vs 64 bit:** A few micro, small, and medium instances are still available to use as 32-bit architecture. You’ll be using 64-bit EC2 (“amd64”) instances nowadays, though smaller instances still support 32 bit (“i386”). Use 64 bit unless you have legacy constraints or other good reasons to use 32.
 -	**HVM vs PV:** There are two kinds of virtualization technology used by EC2, [hardware virtual machine (HVM) and paravirtual (PV)](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/virtualization_types.html). Historically, PV was the usual type, but [now HVM is becoming the standard](https://www.opswat.com/blog/aws-2015-why-you-need-switch-pv-hvm). If you want to use the newest instance types, you must use HVM. See the [instance type matrix](https://aws.amazon.com/amazon-linux-ami/instance-type-matrix/) for details.
@@ -1665,12 +1665,11 @@ EMR
 -	EMR relies on many versions of Hadoop and other supporting software. Be sure to check [which versions are in use](https://docs.aws.amazon.com/ElasticMapReduce/latest/ReleaseGuide/emr-release-components.html).
 -	⏱Off-the-shelf EMR and Hadoop can have significant overhead when compared with efficient processing on a single machine. If your data is small and performance matters, you may wish to consider alternatives, as [this post](http://aadrake.com/command-line-tools-can-be-235x-faster-than-your-hadoop-cluster.html) illustrates.
 -	Python programmers may want to take a look at Yelp’s [mrjob](https://github.com/Yelp/mrjob).
--	💸**Hourly pricing roundoff:** Since EMR jobs are billed at one-hour granularity, considering changing the number and/or type of instances that your job runs in order to best make use of that time slice (fewer / smaller instances to make more efficient use of an undersubscribed hour, more / larger instances to reduce your job’s runtime).
 -	It takes time to tune performance of EMR jobs, which is why third-party services such as [Qubole’s data service](https://www.qubole.com/mapreduce-as-a-service/) are gaining popularity as ways to improve performance or reduce costs.
 
 ### EMR Gotchas and Limitations
 
--	💸❗**EMR costs** can pile up quickly since it involves lots of instances, efficiency can be poor depending on cluster configuration and choice of workload, and accidents like hung jobs are costly. See the [section on EC2 cost management](#ec2-cost-management), especially the tips there about Spot instances and avoiding hourly billing. [This blog post](http://engineering.bloomreach.com/strategies-for-reducing-your-amazon-emr-costs/) has additional tips.
+-	💸❗**EMR costs** can pile up quickly since it involves lots of instances, efficiency can be poor depending on cluster configuration and choice of workload, and accidents like hung jobs are costly. See the [section on EC2 cost management](#ec2-cost-management), especially the tips there about Spot instances. [This blog post](http://engineering.bloomreach.com/strategies-for-reducing-your-amazon-emr-costs/) has additional tips, but was written prior to the shift to per-second billing.
 -	💸 Beware of “double-dipping”. With EMR, you pay for the EC2 capacity and the service fees. In addition, EMR syncs task logs to S3, which means you pay for the storage and **PUT requests** at [S3 standard rates](https://aws.amazon.com/s3/pricing/#Request_Pricing). While the log files tend to be relatively small, every Hadoop job, depending on the size, generates thousands of log files that can quickly add up to thousands of dollars on the AWS bill. YARN’s [log aggregation](http://hortonworks.com/blog/simplifying-user-logs-management-and-access-in-yarn/) is not available on EMR.
 
 Kinesis Streams
@@ -2116,7 +2115,6 @@ Billing and Cost Management
 	-	There are two types of Reserved Instances - [Standard and Convertible](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/reserved-instances-types.html). If you purchase excess Standard Reserved Instances, you may offer to “sell back” unused Reserved Instances via the [Reserved Instance Marketplace](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ri-market-selling-guide.html), this allows you to potentially recoup the cost of unused EC2 compute instance hours by selling them to other AWS customers.
 	-	Instance reservations are not tied to specific EC2 instances - they are applied at the billing level to eligible compute hours as they are consumed across all of the instances in an account.
 	-	📜There have been scattered reports of Convertible RI purchases needing to be exercised in a block-- namely, if you buy five convertible RIs in one purchase, you can't convert just two of them. Reach out to your account manager for clarification if this may impact you.
--	**Hourly billing waste:** EC2 instances are [billed in instance-hours](https://aws.amazon.com/ec2/faqs/#How_will_I_be_charged_and_billed_for_my_use_of_Amazon_EC2) — rounded up to the nearest full hour! For long-lived instances, this is not a big worry, but for large transient deployments, like EMR jobs or test deployments, this can be a significant expense. Never deploy many instances and terminate them after only a few minutes. In fact, if transient instances are part of your regular processing workflow, you should put in protections or alerts to check for this kind of waste.
 -	If you have multiple AWS accounts and have configured them to roll charges up to one account using the “Consolidated Billing” feature, you can expect *unused* Reserved Instance hours from one account to be applied to matching (region, availability zone, instance type) compute hours from another account.
 -	If you have multiple AWS accounts that are linked with Consolidated Billing, plan on using reservations, and want unused reservation capacity to be able to apply to compute hours from other accounts, you’ll need to create your instances in the availability zone with the same *name* across accounts. Keep in mind that when you have done this, your instances may not end up in the same *physical* data center across accounts - Amazon shuffles availability zones names across accounts in order to equalize resource utilization.
 -	Make use of dynamic [Auto Scaling](#auto-scaling), where possible, in order to better match your cluster size (and cost) to the current resource requirements of your service.