projects / proxmox-backup.git / blame
| Commit | Line | Data |
|---|---|---|
| 04e24b14 DW |
1 | Terminology |
| 2 | =========== | |
| 3 | ||
| 4 | Backup Content | |
| 5 | -------------- | |
| 6 | ||
| 7 | When doing deduplication, there are different strategies to get | |
| 8 | optimal results in terms of performance and/or deduplication rates. | |
| 9 | Depending on the type of data, it can be split into *fixed* or *variable* | |
| 10 | sized chunks. | |
| 11 | ||
| 12 | Fixed sized chunking requires minimal CPU power, and is used to | |
| 13 | backup virtual machine images. | |
| 14 | ||
| 15 | Variable sized chunking needs more CPU power, but is essential to get | |
| 16 | good deduplication rates for file archives. | |
| 17 | ||
| 18 | The Proxmox Backup Server supports both strategies. | |
| 19 | ||
| 20 | ||
| 21 | Image Archives: ``<name>.img`` | |
| 22 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
| 23 | ||
| 24 | This is used for virtual machine images and other large binary | |
| 25 | data. Content is split into fixed-sized chunks. | |
| 26 | ||
| 27 | ||
| 28 | File Archives: ``<name>.pxar`` | |
| 29 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
| 30 | ||
| 31 | .. see https://moinakg.wordpress.com/2013/06/22/high-performance-content-defined-chunking/ | |
| 32 | ||
| 33 | A file archive stores a full directory tree. Content is stored using | |
| 34 | the :ref:`pxar-format`, split into variable-sized chunks. The format | |
| 35 | is optimized to achieve good deduplication rates. | |
| 36 | ||
| 37 | ||
| 38 | Binary Data (BLOBs) | |
| 39 | ~~~~~~~~~~~~~~~~~~~ | |
| 40 | ||
| 41 | This type is used to store smaller (< 16MB) binary data such as | |
| 42 | configuration files. Larger files should be stored as image archive. | |
| 43 | ||
| 44 | .. caution:: Please do not store all files as BLOBs. Instead, use the | |
| 45 | file archive to store whole directory trees. | |
| 46 | ||
| 47 | ||
| 48 | Catalog File: ``catalog.pcat1`` | |
| 49 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
| 50 | ||
| 51 | The catalog file is an index for file archives. It contains | |
| 52 | the list of files and is used to speed up search operations. | |
| 53 | ||
| 54 | ||
| 55 | The Manifest: ``index.json`` | |
| 56 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
| 57 | ||
| 58 | The manifest contains the list of all backup files, their | |
| 59 | sizes and checksums. It is used to verify the consistency of a | |
| 60 | backup. | |
| 61 | ||
| 62 | ||
| 63 | Backup Type | |
| 64 | ----------- | |
| 65 | ||
| 66 | The backup server groups backups by *type*, where *type* is one of: | |
| 67 | ||
| 68 | ``vm`` | |
| 69 | This type is used for :term:`virtual machine`\ s. Typically | |
| 70 | consists of the virtual machine's configuration file and an image archive | |
| 71 | for each disk. | |
| 72 | ||
| 73 | ``ct`` | |
| 74 | This type is used for :term:`container`\ s. Consists of the container's | |
| 75 | configuration and a single file archive for the filesystem content. | |
| 76 | ||
| 77 | ``host`` | |
| 78 | This type is used for backups created from within the backed up machine. | |
| 79 | Typically this would be a physical host but could also be a virtual machine | |
| 80 | or container. Such backups may contain file and image archives, there are no restrictions in this regard. | |
| 81 | ||
| 82 | ||
| 83 | Backup ID | |
| 84 | --------- | |
| 85 | ||
| 86 | A unique ID. Usually the virtual machine or container ID. ``host`` | |
| 87 | type backups normally use the hostname. | |
| 88 | ||
| 89 | ||
| 90 | Backup Time | |
| 91 | ----------- | |
| 92 | ||
| 93 | The time when the backup was made. | |
| 94 | ||
| 95 | ||
| 96 | Backup Group | |
| 97 | ------------ | |
| 98 | ||
| 99 | The tuple ``<type>/<ID>`` is called a backup group. Such a group | |
| 100 | may contain one or more backup snapshots. | |
| 101 | ||
| 102 | ||
| 103 | Backup Snapshot | |
| 104 | --------------- | |
| 105 | ||
| 106 | The triplet ``<type>/<ID>/<time>`` is called a backup snapshot. It | |
| 107 | uniquely identifies a specific backup within a datastore. | |
| 108 | ||
| 109 | .. code-block:: console | |
| 110 | :caption: Backup Snapshot Examples | |
| 111 | ||
| 112 | vm/104/2019-10-09T08:01:06Z | |
| 113 | host/elsa/2019-11-08T09:48:14Z | |
| 114 | ||
| 115 | As you can see, the time format is RFC3399_ with Coordinated | |
| 116 | Universal Time (UTC_, identified by the trailing *Z*). | |
| 117 | ||
| 118 |