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======== |
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Glossary |
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======== |
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.. if you add new entries, keep the alphabetical sorting! |
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.. glossary:: |
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:sorted: |
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ballooning |
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A term describing runtime, dynamic changes to an instance's memory, |
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without having to reboot the instance. Depending on the hypervisor |
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and configuration, the changes need to be initiated manually, or |
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they can be automatically initiated by the hypervisor based on the |
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node and instances memory usage. |
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BE parameter |
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BE stands for *backend*. BE parameters are hypervisor-independent |
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instance parameters such as the amount of RAM/virtual CPUs it has |
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been allocated. |
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DRBD |
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A block device driver that can be used to build RAID1 across the |
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network or even shared storage, while using only locally-attached |
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storage. |
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HV parameter |
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HV stands for *hypervisor*. HV parameters are the ones that describe |
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the virtualization-specific aspects of the instance; for example, |
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what kernel to use to boot the instance (if any), or what emulation |
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model to use for the emulated hard drives. |
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HVM |
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Hardware virtualization mode, where the virtual machine is oblivious |
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to the fact that's being virtualized and all the hardware is |
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emulated. |
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LogicalUnit |
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The code associated with an :term:`OpCode`, e.g. the code that |
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implements the startup of an instance. |
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LUXI |
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Local UniX Interface. The IPC method over :manpage:`unix(7)` |
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sockets used between the CLI tools/RAPI daemon and the master |
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daemon. |
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OOB |
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*Out of Band*. This term describes methods of accessing a machine |
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(or parts of a machine) not via the usual network connection. For |
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example, accessing a remote server via a physical serial console or |
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via a virtual one IPMI counts as out of band access. |
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OpCode |
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A data structure encapsulating a basic cluster operation; for |
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example, start instance, add instance, etc. |
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PVM |
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(Xen) Para-virtualization mode, where the virtual machine knows it's |
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being virtualized and as such there is no need for hardware |
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emulation or virtualization. |
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SoR |
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*State of Record*. Refers to values/properties that come from an |
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authoritative configuration source. For example, the maximum VCPU |
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over-subscription ratio is a *SoR* value, but the current |
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over-subscription ration (based on how many instances live on the |
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node) is a :term:`SoW` value. |
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SoW |
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*State of the World*. Refers to values that describe directly the |
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world, as opposed to values that come from the |
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configuration. Contrast with :term:`SoR`. |
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tmem |
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Xen Transcendent Memory |
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(http://en.wikipedia.org/wiki/Transcendent_memory). It is a |
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mechanism used by Xen to provide memory over-subscription. |
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watcher |
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:command:`ganeti-watcher` is a tool that should be run regularly |
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from cron and takes care of restarting failed instances, restarting |
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secondary DRBD devices, etc. For more details, see the man page |
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:manpage:`ganeti-watcher(8)`. |
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