osd: clarify osd scenarios

Co-Authored-By: Rachana Patel <racpatel@redhat.com>
Signed-off-by: Sébastien Han <seb@redhat.com>

group_vars/common-coreoss.sample

@@ -14,3 +14,4 @@ dummy:
 #pypy_binary_directory: /opt/bin
 #pip_url: https://bootstrap.pypa.io/get-pip.py
 #local_temp_directory: /tmp
+

group_vars/osds.sample

@@ -7,9 +7,18 @@
 # file as a good configuration file when no variable in it.
 dummy:
 
+# Variables here are applicable to all host groups NOT roles
+
+# This sample file generated by generate_group_vars_sample.sh
+
+# Dummy variable to avoid error because ansible does not recognize the
+# file as a good configuration file when no variable in it.
+#dummy:
+
 # You can override default vars defined in defaults/main.yml here,
 # but I would advice to use host or group vars instead
 
+
 ###########
 # GENERAL #
 ###########
@@ -22,10 +31,22 @@ dummy:
 # will copy the admin key to the /etc/ceph/ directory
 #copy_admin_key: false
 
+
 ####################
 # OSD CRUSH LOCATION
 ####################
 
+# /!\
+#
+# BE EXTREMELY CAREFUL WITH THIS OPTION
+# DO NOT USE IT UNLESS YOU KNOW WHAT YOU ARE DOING
+#
+# /!\
+#
+# It is probably best to keep this option to 'false' as the default
+# suggests it. This option should only be used while doing some complex
+# CRUSH map. It allows you to force a specific location for a set of OSDs.
+#
 # The following options will build a ceph.conf with OSD sections
 # Example:
 # [osd.X]
@@ -40,6 +61,7 @@ dummy:
 #crush_location: false
 #osd_crush_location: "'root={{ ceph_crush_root }} rack={{ ceph_crush_rack }} host={{ ansible_hostname }}'"
 
+
 ##############
 # CEPH OPTIONS
 ##############
@@ -55,52 +77,61 @@ dummy:
 #
 
 
-# !! WARNING !!
-#
-# /!\ ENABLE ONLY ONE SCENARIO AT A TIME /!\
-#
-# !! WARNING !!
+# Declare devices to be used as OSDs
+# All scenario(except 3rd) inherit from the following device declaration
 
-# Declare devices
-# All the scenarii inherit from the following device declaration
-#
 #devices:
 #  - /dev/sdb
 #  - /dev/sdc
+#  - /dev/sdd
+#  - /dev/sde
 
+
+#'osd_auto_discovery'  mode prevents you from filling out the 'devices' variable above.
+#  You can use this option with First and Forth and Fifth OSDS scenario.
 # Device discovery is based on the Ansible fact 'ansible_devices'
 # which reports all the devices on a system. If chosen all the disks
 # found will be passed to ceph-disk. You should not be worried on using
 # this option since ceph-disk has a built-in check which looks for empty devices.
 # Thus devices with existing partition tables will not be used.
-# This mode prevents you from filling out the 'devices' variable above.
 #
 #osd_auto_discovery: false
 
+
+# !! WARNING !!
+# #
+# # /!\ ENABLE ONLY ONE SCENARIO AT A TIME /!\
+# #
+# #  !! WARNING !!
+#
+
 # I. First scenario: journal and osd_data on the same device
 # Use 'true' to enable this scenario
 # This will collocate both journal and data on the same disk
 # creating a partition at the beginning of the device
+# List devices under 'devices' variable above or choose 'osd_auto_discovery'
+
 
 #journal_collocation: false
 
 
-# II. N journal devices for N OSDs
-# Use 'true' to enable this scenario
-#
+# II.  Second scenario:  N journal devices for N OSDs
+# Use 'true' for 'raw_multi_journal' to enable this scenario
+# List devices under 'devices' variable above and 
+# write journal devices for those under 'raw_journal_devices'
 # In the following example:
-# * sdd and sde will get sdb as a journal
-# * sdf and sdg will get sdc as a journal
+# * sdb and sdc will get sdf as a journal
+# * sdd and sde will get sdg as a journal
+
 # While starting you have 2 options:
 # 1. Pre-allocate all the devices
 # 2. Progressively add new devices
-
 #raw_multi_journal: false
 #raw_journal_devices:
-#  - /dev/sdb
-#  - /dev/sdb
-#  - /dev/sdc
-#  - /dev/sdc
+#  - /dev/sdf
+#  - /dev/sdf
+#  - /dev/sdg
+#  - /dev/sdg
 
 
 # III. Use directory instead of disk for OSDs

roles/ceph-osd/defaults/main.yml

@@ -1,7 +1,16 @@
 ---
+# Variables here are applicable to all host groups NOT roles
+
+# This sample file generated by generate_group_vars_sample.sh
+
+# Dummy variable to avoid error because ansible does not recognize the
+# file as a good configuration file when no variable in it.
+dummy:
+
 # You can override default vars defined in defaults/main.yml here,
 # but I would advice to use host or group vars instead
 
+
 ###########
 # GENERAL #
 ###########
@@ -14,10 +23,22 @@ fetch_directory: fetch/
 # will copy the admin key to the /etc/ceph/ directory
 copy_admin_key: false
 
+
 ####################
 # OSD CRUSH LOCATION
 ####################
 
+# /!\
+#
+# BE EXTREMELY CAREFUL WITH THIS OPTION
+# DO NOT USE IT UNLESS YOU KNOW WHAT YOU ARE DOING
+#
+# /!\
+#
+# It is probably best to keep this option to 'false' as the default
+# suggests it. This option should only be used while doing some complex
+# CRUSH map. It allows you to force a specific location for a set of OSDs.
+#
 # The following options will build a ceph.conf with OSD sections
 # Example:
 # [osd.X]
@@ -32,6 +53,7 @@ copy_admin_key: false
 crush_location: false
 osd_crush_location: "'root={{ ceph_crush_root }} rack={{ ceph_crush_rack }} host={{ ansible_hostname }}'"
 
+
 ##############
 # CEPH OPTIONS
 ##############
@@ -47,52 +69,61 @@ cephx: true
 #
 
 
-# !! WARNING !!
-#
-# /!\ ENABLE ONLY ONE SCENARIO AT A TIME /!\
-#
-# !! WARNING !!
+# Declare devices to be used as OSDs
+# All scenario(except 3rd) inherit from the following device declaration
 
-# Declare devices
-# All the scenarii inherit from the following device declaration
-#
 #devices:
 #  - /dev/sdb
 #  - /dev/sdc
+#  - /dev/sdd
+#  - /dev/sde
 
+
+#'osd_auto_discovery'  mode prevents you from filling out the 'devices' variable above.
+#  You can use this option with First and Forth and Fifth OSDS scenario.
 # Device discovery is based on the Ansible fact 'ansible_devices'
 # which reports all the devices on a system. If chosen all the disks
 # found will be passed to ceph-disk. You should not be worried on using
 # this option since ceph-disk has a built-in check which looks for empty devices.
 # Thus devices with existing partition tables will not be used.
-# This mode prevents you from filling out the 'devices' variable above.
 #
 osd_auto_discovery: false
 
+
+# !! WARNING !!
+# #
+# # /!\ ENABLE ONLY ONE SCENARIO AT A TIME /!\
+# #
+# #  !! WARNING !!
+#
+
 # I. First scenario: journal and osd_data on the same device
 # Use 'true' to enable this scenario
 # This will collocate both journal and data on the same disk
 # creating a partition at the beginning of the device
+# List devices under 'devices' variable above or choose 'osd_auto_discovery'
+
 
 journal_collocation: false
 
 
-# II. N journal devices for N OSDs
-# Use 'true' to enable this scenario
-#
+# II.  Second scenario:  N journal devices for N OSDs
+# Use 'true' for 'raw_multi_journal' to enable this scenario
+# List devices under 'devices' variable above and 
+# write journal devices for those under 'raw_journal_devices'
 # In the following example:
-# * sdd and sde will get sdb as a journal
-# * sdf and sdg will get sdc as a journal
+# * sdb and sdc will get sdf as a journal
+# * sdd and sde will get sdg as a journal
+
 # While starting you have 2 options:
 # 1. Pre-allocate all the devices
 # 2. Progressively add new devices
-
 raw_multi_journal: false
 #raw_journal_devices:
-#  - /dev/sdb
-#  - /dev/sdb
-#  - /dev/sdc
-#  - /dev/sdc
+#  - /dev/sdf
+#  - /dev/sdf
+#  - /dev/sdg
+#  - /dev/sdg
 
 
 # III. Use directory instead of disk for OSDs