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At its core the flavors in our openstack-platforms are named with the following format: "<prefix>.<basic-specs>". The prefix is used to define what kind of VM it is (is it a prioritized or a regular VM? Does it have support for special CPU functionality or not?), while the "basic-specs" describes how many virtual CPU's and how much memory the VM should have. This results in flavors like so:

• gi1gx1.2c4r: A 1st generation Intel Xeon based general-purpose (g1gx1) VM with 2 CPU cores and 4 GB RAM.
• si1sx1.16c64r: A 1st generation Intel Xeon based low-priority (s1sx1) VM with 16 CPU cores and 64 GB RAM. The low-priority flavors are very suitable for compute-loads that is not time-sensitive. Typically flavors with many CPU-cores do long-running batch-jobs and are prioritized lower than smaller flavors which typically hosts interactive applications.
• pi1px1.4c8r: A 1st generation Intel Xeon based prioritized (p1px1) VM with 4 CPU cores and 8 GB RAM. The prioritized flavors are typically used for VM's hosting user-facing interactive applications to ensure that the application responds in a timely manner even when the same physical CPU's are heavily utilized by other long-term running jobs.

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• prefix: 1-3 letters indication flavor-class
• generation: a digit indicating the flavor generation.
• storage-location: optionally a single letter indicating the default storage-location.

Flavor classes

In our openstack-platforms we currently have the following classes:

• General purpose compute:
  • gigx: based on Intel x86 Xeon CPU's
• Prioritized compute. Used for some applications where short response-times are crucial, and it is proven that the general purpose is not sufficient.
  • pipx: based on Intel x86 Xeon CPU's
• Scavenger compute. For compute-loads which is not time-sensitive, but it is nice with as much CPU as possible, the schavenger class allows us to allocate many CPU's that can be heavily utilized without affecting time-sensitive applications running on the same hardware.
  • sisx: based on Intel x86 Xeon CPU's
• Dedicated compute. Some compute-nodes need dedicated hardware for predictible performance. 
  • didx: based on Intel x86 Xeon CPU's
  • de: based on AMD EPYC CPU's.

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The generation-number is used to different various CPU-generations from each other. We currently employ two numbering-schemes; one for Intel-based flavors and one for AMD EPYC based flavors.

Intel Xeon based flavors:

The intel-based flavors can currently exist in 5 different generations. The following table lists the generations, and some of the functionality the generations provides.

Gen	CPU architecture	AES-acecleration	AVX	AVX2	AVX512 1.generation	AVX512 2.generation
1	Westmere
2	Sandy-Bridge
3	Haswell
4	Sky-Lake
5	Cascade-Lake

AMD EPYC based flavors:

Storage locations

Extended specifications

Custom flavors

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