+ :sorted:
+
+ ballooning
+ A term describing runtime, dynamic changes to an instance's memory,
+ without having to reboot the instance. Depending on the hypervisor
+ and configuration, the changes need to be initiated manually, or
+ they can be automatically initiated by the hypervisor based on the
+ node and instances memory usage.
+
+ BE parameter
+ BE stands for *backend*. BE parameters are hypervisor-independent
+ instance parameters such as the amount of RAM/virtual CPUs it has
+ been allocated.
+
+ DRBD
+ A block device driver that can be used to build RAID1 across the
+ network or even shared storage, while using only locally-attached
+ storage.
+
+ HV parameter
+ HV stands for *hypervisor*. HV parameters are the ones that describe
+ the virtualization-specific aspects of the instance; for example,
+ what kernel to use to boot the instance (if any), or what emulation
+ model to use for the emulated hard drives.