Metadata-Version: 2.1
Name: backy
Version: 2.4.2
Summary: Block-based backup and restore utility for virtual machine images
Home-page: https://bitbucket.org/flyingcircus/backy
Author: Christian Theune <ct@flyingcircus.io>, Christian Kauhaus <kc@flyingcircus.io>, Daniel Kraft <daniel.kraft@d9t.de>
Author-email: mail@flyingcircus.io
License: GPL-3
Description: ========
        Overview
        ========
        
        Backy is a block-based backup and restore utility for virtual machine images.
        
        Backy is intended to be:
        
        * space-, time-, and network-efficient
        * trivial to restore
        * reliable.
        
        To achieve this, we rely on:
        
        * space-efficient storages (CoW filesystems, content-hashed chunking)
        * using a snapshot-capable source for our volumes (i.e. Ceph RBD)
          that allows easy extraction of changes between snapshots,
        * leverage proven, existing low-level tools,
        * keep the code-base small, simple, and well-tested.
        
        We also have a few ground rules for the implementation:
        
        * VM data is stored self-contained on the filesystem and can be
          moved between servers using regular FS tools like copy, rsync, or such.
        
        * No third party daemons are required to interact with backy: no database
          server. The scheduler daemon is only responsible for scheduling and simply
          calls regular CLI commands to perform a backup. Backy may interact with
          external daemons like Ceph or Consul, depending on the source storage
          implementation.
        
        
        Operations
        ==========
        
        Full restore
        ------------
        
        Check which revision to restore::
        
          $ backy -b /srv/backy/<vm> status
        
        Maybe set up the Ceph environment - depending on your configuration::
        
          $ export CEPH_ARGS="--id $HOSTNAME"
        
        Restore the full image through a Pipe::
        
          $ backy restore -r <revision> - | rbd import - <pool>/<rootimage>
        
        Restoring individual files
        --------------------------
        
        Backy provides an NBD server to access backups through a mountable device::
        
          $ cd /srv/backy/$vm
          $ backy nbd-server
        
        In a different shell you can now mount this::
        
          $ nbd-client -N <revision> localhost 9000 /dev/nbd0
          $ mkdir  -p /mnt/restore/<vm>
          $ mount -r /dev/nbd0p1 /mnt/restore/<vm>
        
        When done::
        
          $ umount /mnt/restore/<vm>
          $ nbd-client -d /dev/nbd0
        
        Also stop the nbd-server with Ctrl-C.
        
        
        Setting up backy
        ----------------
        
        #. Create a sufficiently large backup partition using a COW-capable filesystem
           like btrfs and mount it under `/srv/backy`.
        
        #. Create a configuration file at `/etc/backy.conf`. See man page for details.
        
        #. Start the scheduler with your favourite init system::
        
              backy -l /var/log/backy.log scheduler -c /path/to/backy.conf
        
           The scheduler runs in the foreground until it is shot by SIGTERM.
        
        #. Set up monitoring using `backy check`.
        
        #. Set up log rotation for `/var/log/backy.conf` and `/srv/backy/*/backy.log`.
        
        The file paths given above match the built-in defaults, but paths are fully
        configurable.
        
        
        Features
        ========
        
        Telnet shell
        ------------
        
        Telnet into localhost port 6023 to get an interactive console. The console can
        currently be used to inspect the scheduler's live status.
        
        
        Self-check
        ----------
        
        Backy includes a self-checking facility. Invoke `backy check` to see if there is
        a recent revision present for all configured backup jobs::
        
           $ backy check
           OK: 9 jobs within SLA
        
        Both output and exit code are suited for processing with Nagios-compatible
        monitoring systems.
        
        
        Pluggable backup sources
        ------------------------
        
        Backy comes with a number of plug-ins which define block-file like sources:
        
        - **file** extracts data from simple image files living on a regular file
          system.
        - **ceph-rbd** pulls data from RBD images using Ceph features like snapshots.
        - **flyingcircus** is an extension to the `ceph-rbd` source which we use
          internally on the `Flying Circus`_ hosting platform. It uses advanced features
          like Consul integration.
        
        .. _Flying Circus: http://flyingcircus.io/
        
        It should be easy to write plug-ins for additional sources.
        
        
        Adaptive verification
        ---------------------
        
        Backy always verifies freshly created backups. Verification scale depends on
        the source type: file-based sources get fully verified. Ceph-based sources are
        verified based on random samples for runtime reasons.
        
        Zero-configuration scheduling
        -----------------------------
        
        The backy scheduler is intended to run continuously. It will spread jobs
        according to the configured run intervals over the day. After resuming from an
        interruption, it will reschedule missed jobs so that SLAs are still kept if
        possible.
        
        Backup jobs can be triggered at specific times as well: just invoke `backy
        backup` manually.
        
        
        Performance
        ===========
        
        Backy is designed to use all of the available storage and network bandwidth by
        running several instances in parallel. The backing storage must be prepared for
        this kind of (mixed) load. Finding optimal settings needs a bit of experimentation
        given that hardware and load profiles differ from site to site. The following
        section contains a few points to start off.
        
        Storage backend
        ---------------
        
        If the backing storage is a RAID array, its stripe size should be aligned with
        the filesystem. We have made good experiences with 256k stripes. Also check for
        512B/4K block misalignments on HDDs. We're using it usually with RAID-6 and have
        seen reasonable performance with both hardware and software RAID.
        
        Filesystem
        ----------
        
        We generally recommend XFS since it provides a high degree of parallelism and is
        able to handle very large directories well.
        
        Note that the standard `cfq` I/O scheduler is not a good pick for
        highly parallel bulk I/O on multiple drives. Use `deadline` or `noop`.
        
        Kernel
        ------
        
        Since backy performs a lot of metadata operations, make sure that inodes and
        dentries are not evicted from the VFS cache too early. We found that lowering
        the `vm.vfs_cache_pressure` sysctl can make quite a difference in total backup
        performance. We're currently getting good results setting it to `10`.
        You may also want to increase `vm.min_free_kbytes` to avoid page allocation
        errors on 10 GbE network interfaces.
        
        
        Authors
        =======
        
        * Christian Theune <ct@flyingcircus.io>
        * Christian Kauhaus <kc@flyingcircus.io>
        * Daniel Kraft <daniel.kraft@d9t.de>
        
        
        License
        =======
        
        GPLv3
        
        
        Links
        =====
        
        * `Bitbucket repository <https://bitbucket.org/flyingcircus/backy>`_
        * `PyPI page <https://pypi.python.org/pypi/backy>`_
        * `Online docs <http://pythonhosted.org/backy/>`_
        * `Build server <https://builds.flyingcircus.io/job/backy/>`_
        
        .. vim: set ft=rst spell spelllang=en sw=3:
        
        =========
        Changelog
        =========
        
        2.4.2 (2019-04-17)
        ==================
        
        - Optimize handling offline/deletion pending VMs: don't just timeout. Take
          snapshots and make backups (as long as the image exists).
        
        - Documentation update about performance implications.
        
        - Clean up build system instrumentation to get our Jenkins going again.
        
        
        2.4.1 (2018-12-06)
        ==================
        
        - Optimization: bundle 'unlink' calls to improve cache locality of VFS metadata
        
        - Optimization: load all known chunks at startup to avoid further seeky IO
          and large metadata parsing, this also speeds up purges.
        
        - Reduce OS VFS cache trashing by explicitly indicating data we don't expect
          to read again.
        
        
        2.4 (2018-11-30)
        ================
        
        - Add support for Ceph Jewel's --whole-object diff export. (#24636)
        
        - Improve garbage collection of old snapshot requests. (#100024)
        
        - Switch to a new chunked store format: remove one level of directories
          to massively reduce seeky IO.
        
        - Reorder and improve potentially seeky IOPS in the per-chunk write effort.
          Do not create directories lazily.
        
        - Require Python 3.6.
        
        2.3 (2018-05-16)
        ================
        
        - Add major operational support for handling inconsistencies.
        
        - Operators can mark revisions as 'distrusted', either all for a backup, or
          individual revisions or time ranges.
        
        - If the newest revision is distrusted then we always perform a full backup
          instead of a differential backup.
        
        - If there is any revision that is distrusted then every chunk will be written
          even if it exists (once during a backup, identical chunks within a backup will
          be trusted once written).
        
        - Implement an explicit verification procedure that will automatically trigger
          after a backup and will verify distrusted revisions and either delete them or
          mark them as verified.
        
        - Safety belt: always verify content hashes when reading chunks.
        
        - Improve status report logging.
        
        2.2 (2017-08-28)
        ================
        
        - Introduce a new backend storage mechanism, independent of BTRFS: instead of
          using COW, use a directory with content-hashed 4MiB chunks of the file.
          Deduplication happens automatically based on the 4MiB chunks.
        
        - Made the use of fadvise features more opportunistic: don't fail if they are
          not supported by the backend as they are only optimizations anyway.
        
        - Introduce an exponential backoff after a failed backup: instead of retrying
          quickly and thus hogging the queue (in the case that timeouts are involved)
          we now backoff exponentially starting with 2 minutes, then 4, then 8, ...
          until we reach 6 hours as the biggest backoff time.
        
          You can still trigger an explicit run using the telnet "run" command for
          the affected backup. This will put the backup in the run queue immediately
          but will not reset the error counter or backoff interval in case it
          fails again.
        
        - Performance improvement on restore: don't read the restore target. We don't
          have to optimize CoW in this case. (#28268)
        
        2.1.5 (2016-07-01)
        ==================
        
        - Bugfix release: fix data corruption bug in the new full-always mode. (FC
          #21963)
        
        
        2.1.4 (2016-06-20)
        ==================
        
        - Add "full-always" flag to Ceph and Flyingcircus sources. (FC #21960)
        
        - Rewrite full backup code to make use of shallow copies to conserve disk space.
          (FC #21960)
        
        
        2.1.3 (2016-06-09)
        ==================
        
        - Fix new timeout to be 5 minutes by default, not 5 days.
        
        - Do not sort blocks any longer: we do not win much from seeking
          over volumes with random blocks anyway and this helps for a more
          even distribution with the new timeout over multiple runs.
        
        
        2.1.2 (2016-06-09)
        ==================
        
        - Fix backup of images containing holes (#33).
        
        - Introduce a (short) timeout for partial image verification. Especially
          very large images and images that are backed up frequently do not profit
          from running for hours to verify them, blocking further backups.
          (FC #21879)
        
        2.1.1 (2016-01-15)
        ==================
        
        - Fix logging bugs.
        
        - Shut down daemon loop cleanly on signal reception.
        
        
        2.1 (2016-01-08)
        ================
        
        - Add optional regex filter to the `jobs` command in the telnet shell.
        
        - Provide list of failed jobs in check output, not only the total number.
        
        - Add `status-interval`, `telnet-addrs`, and `telnet-port` configuration
          options.
        
        - Automatically recover from missing/damaged last or last.rev symlinks (#19532).
        
        - Use `{BASE_DIR}/.lock` as daemon lock file instead of the status file.
        
        - Usability improvements: count jobs, more informative log output.
        
        - Support restoring to block special files like LVM volumes (#31).
        
        
        2.0 (2015-11-06)
        ================
        
        - backy now accepts a `-l` option to specify a log file. If no such option is
          given, it logs to stdout.
        
        - Add `backy find -r REVISION` subcommand to query image paths from shell scripts.
        
        - Fix monitoring bug where partially written images made the check go green
          (#30).
        
        - Greatly improve error handling and detection of failed jobs.
        
        - Performance improvement: turn off line buffering in bulk file operations
          (#20).
        
        - The scheduler reports child failures (exit status > 0) now in the main log.
        
        - Fix fallocate() behaviour on 32 bit systems.
        
        - The `flyingcircus` source type now requires 3 arguments: vm, pool, image.
        
        
        2.0b3 (2015-10-02)
        ==================
        
        - Improve telnet console.
        
        - Provide Nix build script.
        
        - Generate `requirements.txt` automatically from buildout's `versions.cfg`.
        
        
        2.0b2 (2015-09-15)
        ==================
        
        - Introduce scheduler and rework the main backup command. The backy
          command is now only responsible for dealing with individual backups.
        
          It does no longer care about scheduling.
        
          A new daemon and a central configuration file is responsible for that
          now. However, it simply calls out to the existing backy command
          so we can still manually interact with the system even if we do not
          use the daemon.
        
        - Add consul integration for backing up Flying Circus root disk images
          with clean snapshots (by asking fc.qemu to use fs-freeze before preparing
          a Ceph snapshot).
        
        - Switch to shorter UUIDs. Existing files with old UUIDs are compatible.
        
        - Turn the configuration format into YAML. Old files are still compatible.
          New configs will be generated as YAML.
        
        - Performance: defrag all new files automatically to avoid btrfs degrading
          extent performance. It appears this doesn't completely duplicate all CoW
          data. Will have to monitor this in the future.
        
        2.0b1 (2014-07-07)
        ==================
        
        - Clean up docs.
        
        - Add classifiers in setup.py.
        
        - More or less complete rewrite expecting a copy-on-write filesystem as the
          target.
        
        - Flexible backup scheduling using free-form tags.
        
        - Compatible with Python 3.2-3.4.
        
        - Initial open source import as provided by Daniel Kraft (D9T).
        
        .. vim: set ft=rst spell spelllang=en:
        
Keywords: backup
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: Environment :: Console
Classifier: Intended Audience :: System Administrators
Classifier: License :: OSI Approved :: GNU General Public License v3 (GPLv3)
Classifier: Operating System :: POSIX
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.4
Classifier: Topic :: System :: Archiving :: Backup
Provides-Extra: test
