Machine Types / Flavors

Basic Information

SWITCHengines provides different machine types for any possible use case. Do you have high compute workloads? Do you require more memory for your application? No problem!
"Openstack Flavors" give you the ability to design the hardware specifications of your instance. Initially, we provide you with some general information. Please, don't skip this section, it is important to understand the basics!

Definitions

vCPU Number of virtual CPUs
RAM Amount of RAM (GB)
Root Disk Non-persistent disk (if the instance is deleted, the data gets lost)
Volume-backed Root Disk Openstack Volume is created for the root disk (persistent)
GPU Number and type of the GPUs assigned to an instance
Local SSD Local SSD on the hypervisor (passed through to the guest instance)

 

SWITCHengines Flavors Explained


SWITCHengines are historically grown what leads to some confusion when one is getting started with our flavors. We are aware of this fact and try to simplify this in the future. Unfortunately, flavors cannot be easily removed nor renamed what requires careful actions.

A very important decision is the storage of the instance. On a very simplified level, there are two types of instance storage:

  • Root Disk (non-persistent):
    • Defined via flavor option "Root Disk"
    • Non-persistent disk → Data gets deleted if the instance is deleted.
  • Volume-backed Root Disk:
    • An Openstack Volume is the root disk.
    • Defined before creating the instance, i.e. via "Project → Volumes → Volumes → Create Volume"
      or on instance creation time with "Source: Create New Volume"
    • Default in SWITCHengines

When using the SWITCHengines dashboard, by default an new instance is created with a volume-backed root disk. This has several advantages like:

  • More flexibility (Instance resizing is not dependent on the flavor disk size)
  • Data persists over instance deletions
  • Shelving instances is much faster
  • Snapshotting volumes (via Volume Snapshot) is faster than snapshotting instances (via Instance Snapshot)

Implications For the Flavor Selection

  • Snapshotting of volume-backed instances should be done via the Volumes dashboard:
    • "Project → Volumes → Volumes → Volume Menu → Create Snapshot"
    • CLI: 
      openstack volume snapshot create --volume VOL_UUID SNAP_NAME
  • The "Root Disk" property only applies if you select the "Create New Volume: No" on instance launch (not volume-backed root disk).
    This is generally not recommended! Local SSD flavors are the exceptions where it's required to have "Create New Volume: No", see explanation below!

Standard Flavors

The following flavors are the standards and are used the most:

Flavor Name vCPU vRAM (GB) Root Disk (GB) Description Explanation
c1.small
c1.medium
c1.large
c1.xlarge
c1.xxlarge		 1
2
4
8
16		 1
2
4
8
16		 20
20
20
20
20

Simplified resizing within c1 flavor family
(up and down resizing)

Ceph standard disk,
RAM ~ 1GB x CPU
m1.small
m1.medium
m1.large
m1.xlarge
m1.xxlarge		 1
2
4
8
16		 2
4
8
16
32		 20
40
80
160
160		  Increasing ephemeral disk size,
Not downward resizable		 Openstack Defaults,
Ceph standard disk,
RAM ~ 2GB x CPU
n1.small
n1.medium
n1.large
n1.xlarge
n1.xxlarge		 1
2
4
8
16		 4
8
16
32
64		 20
20
20
20
20		 Similar to c1,
Simplified resizing within n1 flavor family		 Ceph standard disk,
RAM ~ 4GB x CPU

 windows.small
windows.medium
windows.large

 1
2
4		 1
2
4		 50
50
50		 Similar to c1 flavors but with 50GB Root Disk 

DEPRECATED [1]

Ceph standard disk

 [1]: Windows instances are not bound to a specific flavor! You can use a c1/m1/n1 flavor that serves your needs. Keep in mind that Windows has a requirement of >50GB disks in order to work properly.

Special Flavors

There are special flavors in SWITCHengines that give you even further functionality. GPU as well as Local SSD flavors need to be enabled for your project in https://engines.admin.switch.ch.

GPU Flavors

GPU flavors take care that your instance is scheduled to the right hypervisor and that the correct number of GPUs are passed to your guest instance.

Flavor Name vCPU RAM (GB) Root Disk (GB) GPU Model Description Explanation
g1.c8r32-p100
g1.c16r64-p100
g1.c24r112-p100

 8
16
24		 32
64
112		 30
30
30		 1
1
1		 P100
P100
P100		  See GPU Support Ceph standard disk
GPU passthrough 
g1.c04r46-1titanxp
g1.c08r92-2titanxp
g1.c16r184-4titanxp
 4
8
16		 46
92
184		 30
30
30		 1
2
4		 Titan XP  See GPU Support Ceph standard disk
GPU passthrough
g1.c04r44-1t4
g1.c08r88-2t4
g1.c16r176-4t4		 4
8
16 		 44
88
176		 30
30
30		 1
2
4		  T4  See GPU Support  Ceph standard disk
GPU passthrough 

See GPU Support for more information about GPUs. 

Local SSD

You have to explicitely use an ephemeral root disk (see above explanation). You can do the following:

  • In Project → Compute → Instances → "Launch Instance"
  • Source:
    • Select Boot Source: Image
    • Create New Volume: No

This is very important! Otherwise, you don't use the local SSD.

Flavor Name vCPU RAM (GB) Root Disk (GB) Description Explanation
 i1.small
i1.medium
i1.large		 1
4
8		 1
8
16		 20
50
50

Local SSD flavor

 Important: [1]
i1.cXrYdZ X  Y Z Local SSD flavor Important: [1]

 [1]: We don't recommend to use local SSDs because of the following pain points:

  • NO data replication
  • No live maintenance (VM has to be turned off on request)
  • Very slow snapshotting
  • No hypervisor migration
  • No resizing is supported by SWITCHengines
  • No migrations are supported by SWITCHengine

Recommendation: ceph-ssd

  • Very good performance
  • 3x replication
  • Easy maintenance
  • Easy snapshotting

In order to install a VM using ceph-ssd, you have to create a volume with ceph-ssd first where you use the required image as a basis. "Project → Volumes → Volumes → Create Volume"