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• Machines cannot be moved between virtualization types
• Older Hydra setups for CHF used m3 on a paravirutal method. Current setups use a HVM m4 instance. Recreating old machines needs to use an old AMI.
  
• Inside the same type, you can change the type from the EC2 dashboard by selecting Action→Instance Setting→Change Instance type. This is scriptableWe currently use HVM. The original Hydra box was PV, but we're not longer using that style of box.

AWS - Instance types

Currently we are using AWS m4 instances on HV virtuzalization. HVM currently supports performance levels that match PV methods and open up the potential for improved network tools or GPU based computingmultiple instance types. Generally for production boxes we use either m4.large or t2.medium instance types.

The m4.large instance type was chosen due to the following requirements

•   Java is RAM hungry and so to make full use of tools like Solr and Fedora 8 GB of RAM was useful
• m class instances have a static CPU value allowing us to have a standard level of performance, as we do not currently have details on usage patterns this seems the safest option.

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• maintain full use of the CPU for intensive tasks

The t2.medium instance was chosen for the following reasons

• Identical RAM profile
• 14% cost reduction on hourly machines
• Baseline CPU limits are lower than m4 (they can burst higher) but this should not ever be an issue in development.
• Reserved pricing is the same so offers no benefit on long term instances.
  

If we do not need the full RAM use for development, t.2 medium instances are approximately 50% of the cost of a m4.large.

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• Approximately 50% of the cost of m4.large instances
• Able to handle usage patterns in bursts of activity rather than sustained heavy load
• Reasonable resources for moderate usage

Some other tools use smaller or larger instances based on needs. Monitoring and update boxes tend to be very small.

AWS - Volume types

In all instances where disk speed is an issue, select general purpose SSDs. If a disk is smaller than 100 GB this also usually easier.

In cases where disk capacity is the primary factor, select either Cold HDD or Throughput HDD volumes. They have a minimum size of 500 GB

• Cold HDDs are slower but half the cost, and in cases where usage is light are preferred.
• Throughput HDDS are faster and should be chosen when disk speed is a larger concern.

Fedora uses a Cold HDD for data storage due to reduced usage and the need to keep costs down.