Synnefo » snf-ganeti

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Glossary

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.. if you add new entries, keep the alphabetical sorting!

.. glossary::

  :sorted:

  ballooning

    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.

  DRBD

    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.

  HVM

    *Hardware Virtualization Mode*. In this mode, the virtual machine is

    oblivious to the fact that it is virtualized and all its hardware is

    emulated.

  LogicalUnit

    The code associated with an :term:`OpCode`; for example, the code that

    implements the startup of an instance.

  LUXI

     Local UniX Interface. The IPC method over :manpage:`unix(7)` sockets used

     between the CLI tools/RAPI daemon and the master daemon.

  OOB

    *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.

  OpCode

    A data structure encapsulating a basic cluster operation; for example: start

    instance, add instance, etc.

  PVM

    (Xen) *Para-virtualization mode*. In this mode, the virtual machine is aware

    that it is virtualized; therefore, there is no need for hardware emulation

    or virtualization.

  SoR

    *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 :term:`SoW` value.

  SoW

    *State of the World*. Refers to values that directly describe the world, as

    opposed to values that come from the configuration (which are considered

    :term:`SoR`).

  tmem

    Xen Transcendent Memory (http://en.wikipedia.org/wiki/Transcendent_memory).

    tmem is a mechanism used by Xen to provide memory over-subscription.

  watcher

    :command:`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

    :manpage:`ganeti-watcher(8)`.

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