- A term describing dynamic changes to an instance’s memory while the instance
is running that don’t require an instance reboot. Depending on the
hypervisor and configuration, changes may be automatically initiated by the
hypervisor (based on the memory usage of the node and instance), or may need
to be initiated manually.
- BE parameter
- BE stands for backend. BE parameters are hypervisor-independent instance
parameters, such as the amount of RAM/virtual CPUs allocated to an instance.
- A block device driver that can be used to build RAID1 across the network or
across shared storage, while using only locally-attached storage.
- HV parameter
- HV stands for hypervisor. HV parameters describe the virtualization-
specific aspects of the instance. For example, a HV parameter might describe
what kernel (if any) to use to boot the instance or what emulation model to
use for the emulated hard drives.
- Hardware Virtualization Mode. In this mode, the virtual machine is
oblivious to the fact that it is virtualized and all its hardware is
- The code associated with an OpCode; for example, the code that
implements the startup of an instance.
- Local UniX Interface. The IPC method over unix(7) sockets used
between the CLI tools/RAPI daemon and the master daemon.
- Out of Band. This term describes methods of accessing a machine (or parts
of a machine) by means other than the usual network connection. Examples
include accessing a remote server via a physical serial console or via a
virtual console. IPMI is also considered OOB access.
- A data structure encapsulating a basic cluster operation; for example: start
instance, add instance, etc.
- (Xen) Para-virtualization mode. In this mode, the virtual machine is aware
that it is virtualized; therefore, there is no need for hardware emulation
- State of Record. Refers to values/properties that come from an
authoritative configuration source. For example, the maximum VCPU over-
subscription ratio is a SoR value, but the current over-subscription ratio
(based upon how many instances live on the node) is a SoW value.
- State of the World. Refers to values that directly describe the world, as
opposed to values that come from the configuration (which are considered
- Xen Transcendent Memory (http://en.wikipedia.org/wiki/Transcendent_memory).
tmem is a mechanism used by Xen to provide memory over-subscription.
- ganeti-watcher is a tool that should be run regularly from
cron. The tool executes tasks such as restarting failed instances and
restarting secondary DRBD devices. For more details, see the man page