221 lines
6.6 KiB
ReStructuredText
221 lines
6.6 KiB
ReStructuredText
===================
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Backup and Recovery
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===================
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Standard backup best practices apply when creating your OpenStack backup
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policy. For example, how often to back up your data is closely related
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to how quickly you need to recover from data loss.
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.. note::
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If you cannot have any data loss at all, you should also focus on a
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highly available deployment. The `OpenStack High Availability
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Guide <http://docs.openstack.org/ha-guide/index.html>`_ offers
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suggestions for elimination of a single point of failure that could
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cause system downtime. While it is not a completely prescriptive
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document, it offers methods and techniques for avoiding downtime and
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data loss.
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Other backup considerations include:
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* How many backups to keep?
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* Should backups be kept off-site?
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* How often should backups be tested?
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Just as important as a backup policy is a recovery policy (or at least
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recovery testing).
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What to Back Up
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~~~~~~~~~~~~~~~
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While OpenStack is composed of many components and moving parts, backing
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up the critical data is quite simple.
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This chapter describes only how to back up configuration files and
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databases that the various OpenStack components need to run. This
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chapter does not describe how to back up objects inside Object Storage
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or data contained inside Block Storage. Generally these areas are left
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for users to back up on their own.
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Database Backups
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~~~~~~~~~~~~~~~~
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The example OpenStack architecture designates the cloud controller as
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the MySQL server. This MySQL server hosts the databases for nova,
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glance, cinder, and keystone. With all of these databases in one place,
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it's very easy to create a database backup:
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.. code-block:: console
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# mysqldump --opt --all-databases > openstack.sql
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If you only want to backup a single database, you can instead run:
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.. code-block:: console
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# mysqldump --opt nova > nova.sql
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where ``nova`` is the database you want to back up.
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You can easily automate this process by creating a cron job that runs
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the following script once per day:
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.. code-block:: bash
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#!/bin/bash
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backup_dir="/var/lib/backups/mysql"
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filename="${backup_dir}/mysql-`hostname`-`eval date +%Y%m%d`.sql.gz"
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# Dump the entire MySQL database
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/usr/bin/mysqldump --opt --all-databases | gzip > $filename
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# Delete backups older than 7 days
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find $backup_dir -ctime +7 -type f -delete
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This script dumps the entire MySQL database and deletes any backups
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older than seven days.
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File System Backups
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~~~~~~~~~~~~~~~~~~~
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This section discusses which files and directories should be backed up
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regularly, organized by service.
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Compute
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-------
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The ``/etc/nova`` directory on both the cloud controller and compute
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nodes should be regularly backed up.
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``/var/log/nova`` does not need to be backed up if you have all logs
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going to a central area. It is highly recommended to use a central
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logging server or back up the log directory.
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``/var/lib/nova`` is another important directory to back up. The
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exception to this is the ``/var/lib/nova/instances`` subdirectory on
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compute nodes. This subdirectory contains the KVM images of running
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instances. You would want to back up this directory only if you need to
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maintain backup copies of all instances. Under most circumstances, you
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do not need to do this, but this can vary from cloud to cloud and your
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service levels. Also be aware that making a backup of a live KVM
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instance can cause that instance to not boot properly if it is ever
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restored from a backup.
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Image Catalog and Delivery
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--------------------------
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``/etc/glance`` and ``/var/log/glance`` follow the same rules as their
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nova counterparts.
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``/var/lib/glance`` should also be backed up. Take special notice of
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``/var/lib/glance/images``. If you are using a file-based back end of
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glance, ``/var/lib/glance/images`` is where the images are stored and
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care should be taken.
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There are two ways to ensure stability with this directory. The first is
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to make sure this directory is run on a RAID array. If a disk fails, the
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directory is available. The second way is to use a tool such as rsync to
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replicate the images to another server:
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.. code-block:: console
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# rsync -az --progress /var/lib/glance/images backup-server:/var/lib/glance/images/
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Identity
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--------
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``/etc/keystone`` and ``/var/log/keystone`` follow the same rules as
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other components.
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``/var/lib/keystone``, although it should not contain any data being
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used, can also be backed up just in case.
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Block Storage
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-------------
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``/etc/cinder`` and ``/var/log/cinder`` follow the same rules as other
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components.
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``/var/lib/cinder`` should also be backed up.
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Networking
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----------
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``/etc/neutron`` and ``/var/log/neutron`` follow the same rules as other
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components.
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``/var/lib/neutron`` should also be backed up.
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Object Storage
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--------------
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``/etc/swift`` is very important to have backed up. This directory
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contains the swift configuration files as well as the ring files and
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ring :term:`builder files <builder file>`, which if lost, render the data
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on your cluster inaccessible. A best practice is to copy the builder files
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to all storage nodes along with the ring files. Multiple backup copies are
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spread throughout your storage cluster.
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Telemetry
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---------
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Back up the ``/etc/ceilometer`` directory containing Telemetry configuration
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files.
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Orchestration
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-------------
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Back up HOT template ``yaml`` files, and the ``/etc/heat/`` directory
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containing Orchestration configuration files.
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Recovering Backups
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~~~~~~~~~~~~~~~~~~
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Recovering backups is a fairly simple process. To begin, first ensure
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that the service you are recovering is not running. For example, to do a
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full recovery of ``nova`` on the cloud controller, first stop all
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``nova`` services:
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.. code-block:: console
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# stop nova-api
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# stop nova-cert
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# stop nova-consoleauth
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# stop nova-novncproxy
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# stop nova-objectstore
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# stop nova-scheduler
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Now you can import a previously backed-up database:
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.. code-block:: console
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# mysql nova < nova.sql
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You can also restore backed-up nova directories:
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.. code-block:: console
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# mv /etc/nova{,.orig}
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# cp -a /path/to/backup/nova /etc/
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Once the files are restored, start everything back up:
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.. code-block:: console
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# start mysql
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# for i in nova-api nova-cert nova-consoleauth nova-novncproxy \
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nova-objectstore nova-scheduler
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> do
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> start $i
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> done
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Other services follow the same process, with their respective
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directories and databases.
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Summary
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~~~~~~~
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Backup and subsequent recovery is one of the first tasks system
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administrators learn. However, each system has different items that need
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attention. By taking care of your database, image service, and
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appropriate file system locations, you can be assured that you can
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handle any event requiring recovery.
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