From 057c92fe066c2debec7aa568113922a433b56a26 Mon Sep 17 00:00:00 2001
From: Christian Berendt <berendt@betacloud-solutions.de>
Date: Thu, 2 Jun 2016 15:49:15 +0200
Subject: [PATCH] Document the use of external Ceph journal drives
Change-Id: I3f0873f425f49514e6f086a6baa25dc3a3ee1dd5
Closes-bug: #1560049
---
doc/ceph-guide.rst | 50 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 48 insertions(+), 2 deletions(-)
diff --git a/doc/ceph-guide.rst b/doc/ceph-guide.rst
index 1f892e13ba..2be412ae52 100644
--- a/doc/ceph-guide.rst
+++ b/doc/ceph-guide.rst
@@ -15,8 +15,8 @@ Requirements
* A minimum of 3 hosts for a vanilla deploy
* A minimum of 1 block device per host
-Preparation and Deployment
-==========================
+Preparation
+===========
To prepare a disk for use as a
`Ceph OSD <http://docs.ceph.com/docs/master/man/8/ceph-osd/>`_ you must add a
@@ -47,6 +47,49 @@ usage with Kolla.
1 1049kB 10.7GB 10.7GB KOLLA_CEPH_OSD_BOOTSTRAP
+Using an external journal drive
+-------------------------------
+
+The steps documented above created a journal partition of 5 GByte
+and a data partition with the remaining storage capacity on the same tagged
+drive.
+
+It is a common practice to place the journal of an OSD on a separate
+journal drive. This section documents how to use an external journal drive.
+
+Prepare the storage drive in the same way as documented above:
+
+::
+
+ # <WARNING ALL DATA ON $DISK will be LOST!>
+ # where $DISK is /dev/sdb or something similar
+ parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_FOO 1 -1
+
+To prepare the journal external drive execute the following command:
+
+::
+
+ # <WARNING ALL DATA ON $DISK will be LOST!>
+ # where $DISK is /dev/sdc or something similar
+ parted $DISK -s -- mklabel gpt mkpart KOLLA_CEPH_OSD_BOOTSTRAP_FOO_J 1 -1
+
+.. note::
+
+ Use different suffixes (``_42``, ``_FOO``, ``_FOO42``, ..) to use different external
+ journal drives for different storage drives. One external journal drive can only
+ be used for one storage drive.
+
+.. note::
+
+ The partition labels ``KOLLA_CEPH_OSD_BOOTSTRAP`` and ``KOLLA_CEPH_OSD_BOOTSTRAP_J``
+ are not working when using external journal drives. It is required to use
+ suffixes (``_42``, ``_FOO``, ``_FOO42``, ..). If you want to setup only one
+ storage drive with one external journal drive it is also necessary to use a suffix.
+
+
+Configuration
+=============
+
Edit the [storage] group in the inventory which contains the hostname of the
hosts that have the block devices you have prepped as shown above.
@@ -82,6 +125,9 @@ and add the contents::
osd pool default min size = 1
+Deployment
+==========
+
Finally deploy the Ceph-enabled OpenStack:
::