From 17227cd122c519a8e17531c08b835bf1ccc1ff24 Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Sun, 14 Mar 2010 01:55:19 +0100
Subject: [PATCH] Update documentation for disk adoption
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>
---
doc/admin.rst | 21 +++++++++++++++++++++
man/gnt-instance.sgml | 26 +++++++++++++++++++++-----
2 files changed, 42 insertions(+), 5 deletions(-)
diff --git a/doc/admin.rst b/doc/admin.rst
index 61f572b95..89941c0b4 100644
--- a/doc/admin.rst
+++ b/doc/admin.rst
@@ -326,6 +326,27 @@ one must specify the location of the snapshot. The command is::
Most of the options available for the command :command:`gnt-instance
add` are supported here too.
+Import of foreign instances
++++++++++++++++++++++++++++
+
+There is a possibility to import a foreign instance whose disk data is
+already stored as LVM volumes without going through copying it: the disk
+adoption mode.
+
+For this, ensure that the original, non-managed instance is stopped,
+then create a Ganeti instance in the usual way, except that instead of
+passing the disk information you specify the current volumes::
+
+ gnt-instance add -t plain -n HOME_NODE ... \
+ --disk 0:adopt=lv_name INSTANCE_NAME
+
+This will take over the given logical volumes, rename them to the Ganeti
+standard (UUID-based), and without installing the OS on them start
+directly the instance. If you configure the hypervisor similar to the
+non-managed configuration that the instance had, the transition should
+be seamless for the instance. For more than one disk, just pass another
+disk parameter (e.g. ``--disk 1:adopt=...``).
+
Instance HA features
--------------------
diff --git a/man/gnt-instance.sgml b/man/gnt-instance.sgml
index c898cb504..1436bcc96 100644
--- a/man/gnt-instance.sgml
+++ b/man/gnt-instance.sgml
@@ -75,7 +75,10 @@
<sbr>
<group choice="req">
- <arg rep="repeat">--disk=<replaceable>N</replaceable>:size=<replaceable>VAL</replaceable><arg>,mode=<replaceable>ro|rw</replaceable></arg></arg>
+ <arg rep="repeat">--disk=<replaceable>N</replaceable>:<group choice="req">
+ <arg>size=<replaceable>VAL</replaceable></arg>
+ <arg>adopt=<replaceable>LV</replaceable></arg>
+ </group>,mode=<replaceable>ro|rw</replaceable></arg>
<arg>-s <replaceable>SIZE</replaceable></arg>
</group>
<sbr>
@@ -126,15 +129,28 @@
The <option>disk</option> option specifies the parameters
for the disks of the instance. The numbering of disks starts
at zero, and at least one disk needs to be passed. For each
- disk, at least the size needs to be given, and optionally
- the access mode (read-only or the default of read-write) can
- also be specified. The size is interpreted (when no unit is
- given) in mebibytes. You can also use one of the suffixes
+ disk, either the size or the adoption source needs to be
+ given, and optionally the access mode (read-only or the
+ default of read-write) can also be specified. The size is
+ interpreted (when no unit is given) in mebibytes. You can
+ also use one of the suffixes
<literal>m</literal>, <literal>g</literal> or
<literal>t</literal> to specificy the exact the units used;
these suffixes map to mebibytes, gibibytes and tebibytes.
</para>
+ <para>
+ When using the <option>adopt</option> key in the disk
+ definition, Ganeti will reuse those volumes (instead of
+ creating new ones) as the instance's disks. Ganeti will
+ rename these volumes to the standard format, and (without
+ installing the OS) will use them as-is for the
+ instance. This allows migrating instances from non-managed
+ mode (e.q. plain KVM with LVM) to being managed via
+ Ganeti. Note that this works only for the `plain' disk
+ template (see below for template details).
+ </para>
+
<para>
Alternatively, a single-disk instance can be created via the
<option>-s</option> option which takes a single argument,
--
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