# Overview of Cloud Computing Environments

## Instance Type Overview

### Naming

AWS naming of instance types is broken down here:

![](https://3504452945-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fp8rQlIsJAoT4gb1fg2yr%2Fuploads%2Fgit-blob-06d3b97d2f7a639af6a5278f11430aebb5194efd%2Fcloud6.png?alt=media)

### Choosing an Instance Type

| Question                                                   | Focus on this                                                      |
| ---------------------------------------------------------- | ------------------------------------------------------------------ |
| Does the software utilize multiple cores?                  | mem2\_ssd1\_v2\_<mark style="background-color:orange;">x16</mark>  |
| Is the software GPU optimized?                             | mem2\_ssd1\_<mark style="background-color:orange;">gpu\_x32</mark> |
| How much memory does the software use (per core)?          | <mark style="background-color:green;">mem2</mark>\_ssd1\_v2\_x16   |
| How much disk space is needed for the software (per core)? | mem2\_<mark style="background-color:purple;">ssd1</mark>\_v2\_x16  |
| Always use version 2 of an instance type!                  | mem2\_ssd1\_<mark style="background-color:blue;">v2</mark>\_x16    |

### Instance Classes and Cores

Each class (like **mem1**) is scaled so that each core in an instance has access to the same amount of memory/disk space:

* Example: **mem1\_ssd1\_v2\_x2**:
  * 4 Gb total memory / 2 cores =
  * **2 Gb / Core**
* Example: **mem1\_ssd1\_v2\_x8**:
  * 16 Gb total memory / 8 cores =
  * **2 Gb / core**

## Choosing a Good Instance Type

* Scale usage/instance type according to usage statistics and dataset size
  * If it doesn't utilize all resources
    * Use a smaller instance type
  * Runs out of memory, or is slow
    * Consider using a larger instance type

## Multistep Workflows

* Each stage of a workflow is run by a different set of workers
* Each stage can be customized in terms of instance type

## Resources

[Instance Types Documentation](https://documentation.dnanexus.com/developer/api/running-analyses/instance-types)

[Full Documentation](https://documentation.dnanexus.com/)

To create a support ticket if there are technical issues:

1. Go to the Help header (same section where Projects and Tools are) inside the platform
2. Select "Contact Support"
3. Fill in the Subject and Message to submit a support ticket.