Standard versus Zero-Disk Flavor Comparison

In addition to the vCPU, RAM and IOPS specifications, standard flavor’s already have a persistent boot disk integrated in the offering. For a possible expansion of the storage, e.g. for data and programs, these flavor’s simply add additional volumes. These additional volumes can be combined from different volume offerings, which allow different maximum IOPS. Depending on requirements, one or the other flavor variant can make more sense.

The following table shows the differences between the standard flavors (with disk) and the zero-disk flavors.

Function Standard Flavor’s (with fix size integrated persistent Boot-Disk) G - Flavor’s (Zero-Disk) (with custom sized persistent Boot-Disk Volume) Comment
Resize instance Yes [1] Yes [2]
  • Resize Instance by changing Flavor
  • Standard Flavor only from smaller to larger
  • VM reboot required
Instance Snapshot Yes Yes [3]  
volume snapshot no Yes [3]  
Volume Backup no Yes  


[1]Resize Instance of a Standard Flavor includes always CPU, RAM and Root-Disk size
[2]Resize Instance of a Zero-Disk Flavor includes only CPU and RAM (larger to smaller allowed). Resize of a Boot-Disk Volume only supported in the next OpenStack Release “Stein”
[3](1, 2) Stored in Images: Disk Format: QCOW2, Size: 0 bytes, plus under Volumes => Snapshot, Size of the Boot-Disk e.g. 50 GB