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ec1ae7e6 | 1 | .. _terms: |
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3 | Terminology |
4 | =========== | |
5 | ||
6 | Backup Content | |
7 | -------------- | |
8 | ||
9 | When doing deduplication, there are different strategies to get | |
10 | optimal results in terms of performance and/or deduplication rates. | |
11 | Depending on the type of data, it can be split into *fixed* or *variable* | |
12 | sized chunks. | |
13 | ||
14 | Fixed sized chunking requires minimal CPU power, and is used to | |
15 | backup virtual machine images. | |
16 | ||
17 | Variable sized chunking needs more CPU power, but is essential to get | |
18 | good deduplication rates for file archives. | |
19 | ||
20 | The Proxmox Backup Server supports both strategies. | |
21 | ||
22 | ||
23 | Image Archives: ``<name>.img`` | |
24 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
25 | ||
26 | This is used for virtual machine images and other large binary | |
27 | data. Content is split into fixed-sized chunks. | |
28 | ||
29 | ||
30 | File Archives: ``<name>.pxar`` | |
31 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
32 | ||
33 | .. see https://moinakg.wordpress.com/2013/06/22/high-performance-content-defined-chunking/ | |
34 | ||
35 | A file archive stores a full directory tree. Content is stored using | |
36 | the :ref:`pxar-format`, split into variable-sized chunks. The format | |
37 | is optimized to achieve good deduplication rates. | |
38 | ||
39 | ||
40 | Binary Data (BLOBs) | |
41 | ~~~~~~~~~~~~~~~~~~~ | |
42 | ||
43 | This type is used to store smaller (< 16MB) binary data such as | |
717ce406 | 44 | configuration files. Larger files should be stored as image archives. |
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45 | |
46 | .. caution:: Please do not store all files as BLOBs. Instead, use the | |
717ce406 | 47 | file archive to store entire directory trees. |
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48 | |
49 | ||
50 | Catalog File: ``catalog.pcat1`` | |
51 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
52 | ||
53 | The catalog file is an index for file archives. It contains | |
717ce406 | 54 | the list of included files and is used to speed up search operations. |
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55 | |
56 | ||
57 | The Manifest: ``index.json`` | |
58 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
59 | ||
717ce406 | 60 | The manifest contains a list of all backed up files, and their |
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61 | sizes and checksums. It is used to verify the consistency of a |
62 | backup. | |
63 | ||
64 | ||
65 | Backup Type | |
66 | ----------- | |
67 | ||
68 | The backup server groups backups by *type*, where *type* is one of: | |
69 | ||
70 | ``vm`` | |
717ce406 | 71 | This type is used for :term:`virtual machine`\ s. It typically |
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72 | consists of the virtual machine's configuration file and an image archive |
73 | for each disk. | |
74 | ||
75 | ``ct`` | |
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76 | This type is used for :term:`container`\ s. It consists of the container's |
77 | configuration and a single file archive for the filesystem's contents. | |
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78 | |
79 | ``host`` | |
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80 | This type is used for file/directory backups created from within a machine. |
81 | Typically this would be a physical host, but could also be a virtual machine | |
82 | or container. Such backups may contain file and image archives; there are no | |
83 | restrictions in this regard. | |
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84 | |
85 | ||
86 | Backup ID | |
87 | --------- | |
88 | ||
89 | A unique ID. Usually the virtual machine or container ID. ``host`` | |
90 | type backups normally use the hostname. | |
91 | ||
92 | ||
93 | Backup Time | |
94 | ----------- | |
95 | ||
96 | The time when the backup was made. | |
97 | ||
98 | ||
99 | Backup Group | |
100 | ------------ | |
101 | ||
102 | The tuple ``<type>/<ID>`` is called a backup group. Such a group | |
103 | may contain one or more backup snapshots. | |
104 | ||
ec1ae7e6 | 105 | .. _term_backup_snapshot: |
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106 | |
107 | Backup Snapshot | |
108 | --------------- | |
109 | ||
110 | The triplet ``<type>/<ID>/<time>`` is called a backup snapshot. It | |
111 | uniquely identifies a specific backup within a datastore. | |
112 | ||
113 | .. code-block:: console | |
114 | :caption: Backup Snapshot Examples | |
115 | ||
116 | vm/104/2019-10-09T08:01:06Z | |
117 | host/elsa/2019-11-08T09:48:14Z | |
118 | ||
119 | As you can see, the time format is RFC3399_ with Coordinated | |
120 | Universal Time (UTC_, identified by the trailing *Z*). | |
121 | ||
122 |