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Merge "Consolidating galera recovery documentation"

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271
doc/source/install-guide/ops-galera-recovery.rst
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@ -19,6 +19,277 @@ entire environment.
Upon completion of this command the cluster should be back online an in
a functional state.
Single-node failure
~~~~~~~~~~~~~~~~~~~
If a single node fails, the other nodes maintain quorum and continue to
process SQL requests.
#. Run the following Ansible command to determine the failed node:
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql -h localhost \
-e 'show status like \"%wsrep_cluster_%\";'"
node3_galera_container-3ea2cbd3 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server through
socket '/var/run/mysqld/mysqld.sock' (111)
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
In this example, node 3 has failed.
#. Restart MariaDB on the failed node and verify that it rejoins the
cluster.
#. If MariaDB fails to start, run the **mysqld** command and perform
further analysis on the output. As a last resort, rebuild the
container for the node.
Multi-node failure
~~~~~~~~~~~~~~~~~~
When all but one node fails, the remaining node cannot achieve quorum
and stops processing SQL requests. In this situation, failed nodes that
recover cannot join the cluster because it no longer exists.
#. Run the following Ansible command to show the failed nodes:
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node2_galera_container-49a47d25 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
node3_galera_container-3ea2cbd3 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 18446744073709551615
wsrep_cluster_size 1
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status non-Primary
In this example, nodes 2 and 3 have failed. The remaining operational
server indicates ``non-Primary`` because it cannot achieve quorum.
#. Run the following command to
`rebootstrap <http://galeracluster.com/documentation-webpages/quorumreset.html#id1>`_
the operational node into the cluster.
.. code-block:: shell-session
# mysql -e "SET GLOBAL wsrep_provider_options='pc.bootstrap=yes';"
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 15
wsrep_cluster_size 1
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node3_galera_container-3ea2cbd3 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
node2_galera_container-49a47d25 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
The remaining operational node becomes the primary node and begins
processing SQL requests.
#. Restart MariaDB on the failed nodes and verify that they rejoin the
cluster.
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node3_galera_container-3ea2cbd3 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
#. If MariaDB fails to start on any of the failed nodes, run the
**mysqld** command and perform further analysis on the output. As a
last resort, rebuild the container for the node.
Complete failure
~~~~~~~~~~~~~~~~
If all of the nodes in a Galera cluster fail (do not shutdown
gracefully), then the integrity of the database can no longer be
guaranteed and should be restored from backup. Run the following command
to determine if all nodes in the cluster have failed:
.. code-block:: shell-session
# ansible galera_container -m shell -a "cat /var/lib/mysql/grastate.dat"
node3_galera_container-3ea2cbd3 | success | rc=0 >>
# GALERA saved state
version: 2.1
uuid: 338b06b0-2948-11e4-9d06-bef42f6c52f1
seqno: -1
cert_index:
node2_galera_container-49a47d25 | success | rc=0 >>
# GALERA saved state
version: 2.1
uuid: 338b06b0-2948-11e4-9d06-bef42f6c52f1
seqno: -1
cert_index:
node4_galera_container-76275635 | success | rc=0 >>
# GALERA saved state
version: 2.1
uuid: 338b06b0-2948-11e4-9d06-bef42f6c52f1
seqno: -1
cert_index:
All the nodes have failed if ``mysqld`` is not running on any of the
nodes and all of the nodes contain a ``seqno`` value of -1.
If any single node has a positive ``seqno`` value, then that node can be
used to restart the cluster. However, because there is no guarantee that
each node has an identical copy of the data, it is not recommended to
restart the cluster using the **--wsrep-new-cluster** command on one
node.
Rebuilding a container
~~~~~~~~~~~~~~~~~~~~~~
Sometimes recovering from a failure requires rebuilding one or more
containers.
#. Disable the failed node on the load balancer.
Do not rely on the load balancer health checks to disable the node.
If the node is not disabled, the load balancer will send SQL requests
to it before it rejoins the cluster and cause data inconsistencies.
#. Use the following commands to destroy the container and remove
MariaDB data stored outside of the container. In this example, node 3
failed.
.. code-block:: shell-session
# lxc-stop -n node3_galera_container-3ea2cbd3
# lxc-destroy -n node3_galera_container-3ea2cbd3
# rm -rf /openstack/node3_galera_container-3ea2cbd3/*
#. Run the host setup playbook to rebuild the container specifically on
node 3:
.. code-block:: shell-session
# openstack-ansible setup-hosts.yml -l node3 \
-l node3_galera_container-3ea2cbd3
The playbook will also restart all other containers on the node.
#. Run the infrastructure playbook to configure the container
specifically on node 3:
.. code-block:: shell-session
# openstack-ansible infrastructure-setup.yml \
-l node3_galera_container-3ea2cbd3
The new container runs a single-node Galera cluster, a dangerous
state because the environment contains more than one active database
with potentially different data.
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node3_galera_container-3ea2cbd3 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 1
wsrep_cluster_size 1
wsrep_cluster_state_uuid da078d01-29e5-11e4-a051-03d896dbdb2d
wsrep_cluster_status Primary
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 4
wsrep_cluster_size 2
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 4
wsrep_cluster_size 2
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
#. Restart MariaDB in the new container and verify that it rejoins the
cluster.
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 5
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node3_galera_container-3ea2cbd3 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 5
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 5
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
#. Enable the failed node on the load balancer.
--------------

47
doc/source/install-guide/ops-galera-recoverycomplete.rst
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@ -1,47 +0,0 @@
`Home <index.html>`_ OpenStack-Ansible Installation Guide
Complete failure
----------------
If all of the nodes in a Galera cluster fail (do not shutdown
gracefully), then the integrity of the database can no longer be
guaranteed and should be restored from backup. Run the following command
to determine if all nodes in the cluster have failed:
.. code-block:: shell-session
# ansible galera_container -m shell -a "cat /var/lib/mysql/grastate.dat"
node3_galera_container-3ea2cbd3 | success | rc=0 >>
# GALERA saved state
version: 2.1
uuid: 338b06b0-2948-11e4-9d06-bef42f6c52f1
seqno: -1
cert_index:
node2_galera_container-49a47d25 | success | rc=0 >>
# GALERA saved state
version: 2.1
uuid: 338b06b0-2948-11e4-9d06-bef42f6c52f1
seqno: -1
cert_index:
node4_galera_container-76275635 | success | rc=0 >>
# GALERA saved state
version: 2.1
uuid: 338b06b0-2948-11e4-9d06-bef42f6c52f1
seqno: -1
cert_index:
All the nodes have failed if ``mysqld`` is not running on any of the
nodes and all of the nodes contain a ``seqno`` value of -1.
If any single node has a positive ``seqno`` value, then that node can be
used to restart the cluster. However, because there is no guarantee that
each node has an identical copy of the data, it is not recommended to
restart the cluster using the **--wsrep-new-cluster** command on one
node.
--------------
.. include:: navigation.txt

107
doc/source/install-guide/ops-galera-recoverycontainer.rst
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@ -1,107 +0,0 @@
`Home <index.html>`_ OpenStack-Ansible Installation Guide
Rebuilding a container
----------------------
Sometimes recovering from a failure requires rebuilding one or more
containers.
#. Disable the failed node on the load balancer.
Do not rely on the load balancer health checks to disable the node.
If the node is not disabled, the load balancer will send SQL requests
to it before it rejoins the cluster and cause data inconsistencies.
#. Use the following commands to destroy the container and remove
MariaDB data stored outside of the container. In this example, node 3
failed.
.. code-block:: shell-session
# lxc-stop -n node3_galera_container-3ea2cbd3
# lxc-destroy -n node3_galera_container-3ea2cbd3
# rm -rf /openstack/node3_galera_container-3ea2cbd3/*
#. Run the host setup playbook to rebuild the container specifically on
node 3:
.. code-block:: shell-session
# openstack-ansible setup-hosts.yml -l node3 \
-l node3_galera_container-3ea2cbd3
The playbook will also restart all other containers on the node.
#. Run the infrastructure playbook to configure the container
specifically on node 3:
.. code-block:: shell-session
# openstack-ansible infrastructure-setup.yml \
-l node3_galera_container-3ea2cbd3
The new container runs a single-node Galera cluster, a dangerous
state because the environment contains more than one active database
with potentially different data.
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node3_galera_container-3ea2cbd3 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 1
wsrep_cluster_size 1
wsrep_cluster_state_uuid da078d01-29e5-11e4-a051-03d896dbdb2d
wsrep_cluster_status Primary
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 4
wsrep_cluster_size 2
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 4
wsrep_cluster_size 2
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
#. Restart MariaDB in the new container and verify that it rejoins the
cluster.
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 5
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node3_galera_container-3ea2cbd3 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 5
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 5
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
#. Enable the failed node on the load balancer.
--------------
.. include:: navigation.txt

93
doc/source/install-guide/ops-galera-recoverymulti.rst
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@ -1,93 +0,0 @@
`Home <index.html>`_ OpenStack-Ansible Installation Guide
Multi-node failure
------------------
When all but one node fails, the remaining node cannot achieve quorum
and stops processing SQL requests. In this situation, failed nodes that
recover cannot join the cluster because it no longer exists.
#. Run the following Ansible command to show the failed nodes:
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node2_galera_container-49a47d25 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
node3_galera_container-3ea2cbd3 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 18446744073709551615
wsrep_cluster_size 1
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status non-Primary
In this example, nodes 2 and 3 have failed. The remaining operational
server indicates ``non-Primary`` because it cannot achieve quorum.
#. Run the following command to
`rebootstrap <http://galeracluster.com/documentation-webpages/quorumreset.html#id1>`_
the operational node into the cluster.
.. code-block:: shell-session
# mysql -e "SET GLOBAL wsrep_provider_options='pc.bootstrap=yes';"
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 15
wsrep_cluster_size 1
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node3_galera_container-3ea2cbd3 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
node2_galera_container-49a47d25 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server
through socket '/var/run/mysqld/mysqld.sock' (111)
The remaining operational node becomes the primary node and begins
processing SQL requests.
#. Restart MariaDB on the failed nodes and verify that they rejoin the
cluster.
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql \
-h localhost -e 'show status like \"%wsrep_cluster_%\";'"
node3_galera_container-3ea2cbd3 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
#. If MariaDB fails to start on any of the failed nodes, run the
**mysqld** command and perform further analysis on the output. As a
last resort, rebuild the container for the node.
--------------
.. include:: navigation.txt

45
doc/source/install-guide/ops-galera-recoverysingle.rst
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@ -1,45 +0,0 @@
`Home <index.html>`_ OpenStack-Ansible Installation Guide
Single-node failure
-------------------
If a single node fails, the other nodes maintain quorum and continue to
process SQL requests.
#. Run the following Ansible command to determine the failed node:
.. code-block:: shell-session
# ansible galera_container -m shell -a "mysql -h localhost \
-e 'show status like \"%wsrep_cluster_%\";'"
node3_galera_container-3ea2cbd3 | FAILED | rc=1 >>
ERROR 2002 (HY000): Can't connect to local MySQL server through
socket '/var/run/mysqld/mysqld.sock' (111)
node2_galera_container-49a47d25 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
node4_galera_container-76275635 | success | rc=0 >>
Variable_name Value
wsrep_cluster_conf_id 17
wsrep_cluster_size 3
wsrep_cluster_state_uuid 338b06b0-2948-11e4-9d06-bef42f6c52f1
wsrep_cluster_status Primary
In this example, node 3 has failed.
#. Restart MariaDB on the failed node and verify that it rejoins the
cluster.
#. If MariaDB fails to start, run the **mysqld** command and perform
further analysis on the output. As a last resort, rebuild the
container for the node.
--------------
.. include:: navigation.txt

4
doc/source/install-guide/ops-galera.rst
View File

@ -8,10 +8,6 @@ Galera cluster maintenance
ops-galera-remove.rst
ops-galera-start.rst
ops-galera-recovery.rst
ops-galera-recoverysingle.rst
ops-galera-recoverymulti.rst
ops-galera-recoverycomplete.rst
ops-galera-recoverycontainer.rst
Routine maintenance includes gracefully adding or removing nodes from
the cluster without impacting operation and also starting a cluster