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Diffstat (limited to 'manual/fr/060-backing-up.mdwn')
| -rw-r--r-- | manual/fr/060-backing-up.mdwn | 48 |
1 files changed, 31 insertions, 17 deletions
diff --git a/manual/fr/060-backing-up.mdwn b/manual/fr/060-backing-up.mdwn index 16ccc5d2..ee28d6e2 100644 --- a/manual/fr/060-backing-up.mdwn +++ b/manual/fr/060-backing-up.mdwn @@ -137,8 +137,8 @@ protocol (part of SSH). You need the following to achieve this: exchange for having one of their machines at your place, so that you both can backup remotely. -* An **ssh key** for logging into the server. You _can_ log in using - passwords too, but it is quite cumbersome. +* An **ssh key** for logging into the server. Obnam does not currently + support logging in via passwords. * Enough disk space on the server to hold your backups. @@ -356,6 +356,29 @@ duplicate data is quite coarse (see the `--chunk-size` setting), and so Obnam often doesn't find duplication when it exists, when the changes are small. +De-duplication isn't useful in the following scenarios: + +* A file changes such that things move around within the file. The + (current) Obnam de-duplication is based on non-overlapping chunks + from the beginning of a file. If some data is inserted, Obnam won't + notice that the chunks have shifted around. This can happen, for + example, for disk or ISO images. + +* Files with duplicate data that is not on a chunk boundary. For + example, emails with large attachments. Each email recipient gets + different `Received` headers, which shifts the body and attachments + by different amounts. As a result, Obnam won't notice the + duplication. + +* Data in compressed files, such as `.zip` or `.tar.xz` files. Obnam + doesn't know about the file compression, and only sees the + compressed version of the data. Thus, Obnam won'd de-duplicate it. + +A future version of Obnam will hopefully improve the de-duplication +algorithms. If you see this optimistic paragraph in a version of Obnam +released in 2017 or later, please notify the maintainers. Thank you. + + De-duplication and safety against checksum collisions ----------------------------------------------------- @@ -428,27 +451,18 @@ happen if Obnam is interrupted by the user before it's finished. The Obnam command `force-lock` deals with this situation. It is dangerous, though. If you force open a lock that is in active use by -a running Obnam instance, there will likely to be some stepping of -toes. The result may, in extreme cases, even result in repository -corruption. So be careful. +any running Obnam instance, on any client machine using that +repository, there will likely to be some stepping of toes. The result +may, in extreme cases, even result in repository corruption. So be +careful. If you've decided you can safely do it, this is an example of how to do it: obnam -r /media/backups/tomjon-repo force-lock -Note that some of the locks are per-client, to prevent you from -accidentally running Obnam twice for the same client, which would -result in standing on your own toes: kind of impressive, but -uncomfortable and not recommended. - -If you need to force open a lock for specific client, you can specify -the client name explicitly: - - obnam --client-name magrat \ - -r /media/backups/tomjon-repo force-lock - -(Long line broken to two for typographical reasons.) +It is not currently possibly to only break locks related to one +client. Consistency of live data ------------------------ |