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Introduction
Duplicity is a backup solution supporting a wide range of storage services as backends. It supports many features like encryption, compression, filtering, signing etc. As an extremely cheap cold storage solution, PCA is a first class choice for archiving backups.
How duplicity works
Duplicity produces three kinds of information:
Manifests
They contain the list of files stored in volumes.
Signatures
They contain metadata about these files (checksums) and help detecting content change.
Volumes
They hold the actual data. Their size is configured by the user.
Hot vs Cold storage
While hot storage permits accessing data immediately, cold storage introduces a latency in the retrieval process. In order to work, duplicity requires manifests and signatures to be always available. As a consequence, data to be stored must be split according to the expected availability level. Volume files, representing the largest part of a backup, and the bigger in size, will be pushed to PCA while other lightweight information will be stored in PCS. This is possible to accomplish with duplicity's multibackend feature.
Duplicity version
The features described in the rest of this guide uses the (not yet released) 0.8 version of duplicity.
Install duplicity
Requirements
Adapt the following command and package names to your environment.
$ apt install -y bzr gcc librsync-dev python python-dev python-pip
Get the project's sources
To clone duplicity sources locally, you have to use bzr (pronounced bazaar), launchpad's VCS.
$ bzr branch lp:duplicity
Install duplicity development version
$ pip install setuptools wheel
$ pip install -r requirements.txt
$ python setup.py install
Multibackend setup
Put the following completed information in a config.json file:
1. [
2. {
3. "description": "Cold storage",
4. "url": "pca://duplicity_cold",
5. "env": [
6. {
7. "name": "PCA_AUTHURL",
8. "value": "https://auth.cloud.ovh.net/v3"
9. },
10. {
11. "name": "PCA_AUTHVERSION",
12. "value": "3"
13. },
14. {
15. "name": "PCA_PROJECT_DOMAIN_NAME",
16. "value": "Default"
17. },
18. {
19. "name": "PCA_TENANTID",
20. "value": "<your_tenant_id>"
21. },
22. {
23. "name": "PCA_USERNAME",
24. "value": "<your_username>"
25. },
26. {
27. "name": "PCA_PASSWORD",
28. "value": "<your_password>"
29. },
30. {
31. "name": "PCA_REGIONNAME",
32. "value": "<region_name>"
33. }
34. ],
35. "prefixes": ["cold_"]
36. },
37. {
38. "description": "Hot storage",
39. "url": "swift://duplicity_hot",
40. "env": [
41. {
42. "name": "SWIFT_AUTHURL",
43. "value": "https://auth.cloud.ovh.net/v3"
44. },
45. {
46. "name": "SWIFT_AUTHVERSION",
47. "value": "3"
48. },
49. {
50. "name": "SWIFT_PROJECT_DOMAIN_NAME",
51. "value": "Default"
52. },
53. {
54. "name": "SWIFT_TENANTID",
55. "value": "<your_tenant_id>"
56. },
57. {
58. "name": "SWIFT_USERNAME",
59. "value": "<your_username>"
60. },
61. {
62. "name": "SWIFT_PASSWORD",
63. "value": "<your_password>"
64. },
65. {
66. "name": "SWIFT_REGIONNAME",
67. "value": "<region_name>"
68. }
69. ],
70. "prefixes": ["hot_"]
71. }
72. ]
Run backups
To run your first full backup:
duplicity \
--file-prefix-manifest 'hot_' \
--file-prefix-signature 'hot_' \
--file-prefix-archive 'cold_' \
full \
/what/to/backup 'multi:///path/to/config.json?mode=mirror&onfail=abort'
Then you can make incremental backups of the same path by replacing full with incremental in the previous command.