doc: glossary improvements

These will be used to remove some inline definitions and replace them
with :term:`foo`.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

doc/glossary.rst

@@ -5,37 +5,86 @@ Glossary
 .. if you add new entries, keep the alphabetical sorting!
 
 .. glossary::
+  :sorted:
 
-  BE Parameter
-    BE stands for Backend. BE parameters are hypervisor-independent
+  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.
+
   HVM
-    Hardware virtualization mode, where the virtual machine is
-    oblivious to the fact that's being virtualized and all the
-    hardware is emulated.
+    Hardware virtualization mode, where the virtual machine is oblivious
+    to the fact that's being virtualized and all the hardware is
+    emulated.
 
   LogicalUnit
-    The code associated with an OpCode, e.g. the code that implements
-    the startup of an instance.
+    The code associated with an :term:`OpCode`, e.g. the code that
+    implements the startup of an instance.
 
   LUXI
-     Local UniX Interface. The IPC method over unix sockets used between
-     the cli tools and the master daemon.
+     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) not via the usual network connection. For
+    example, accessing a remote server via a physical serial console or
+    via a virtual one IPMI counts as out of band access.
 
   OpCode
     A data structure encapsulating a basic cluster operation; for
     example, start instance, add instance, etc.
 
   PVM
-    Para-virtualization mode, where the virtual machine knows it's being
-    virtualized and as such there is no need for hardware emulation.
+    (Xen) Para-virtualization mode, where the virtual machine knows it's
+    being virtualized and as such 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 ration (based on how many instances live on the
+    node) is a :term:`SoW` value.
+
+  SoW
+    *State of the World*. Refers to values that describe directly the
+    world, as opposed to values that come from the
+    configuration. Contrast with :term:`SoR`.
+
+  tmem
+    Xen Transcendent Memory
+    (http://en.wikipedia.org/wiki/Transcendent_memory). It is a
+    mechanism used by Xen to provide memory over-subscription.
 
   watcher
-    ``ganeti-watcher`` is a tool that should be run regularly from cron
-    and takes care of restarting failed instances, restarting secondary
-    DRBD devices, etc. For more details, see the man page
+    :command:`ganeti-watcher` is a tool that should be run regularly
+    from cron and takes care of restarting failed instances, restarting
+    secondary DRBD devices, etc. For more details, see the man page
     :manpage:`ganeti-watcher(8)`.
 
+
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+.. Local Variables:
+.. mode: rst
+.. fill-column: 72
+.. End: