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c3370a5f07
UNIX domain sockets: explain why not, see attic issue #259 Symlinks: say that they are backed up as is and not followed, replacement for attic PR #294 Sparse files: explain what the "simple" in simple sparse file support means. Plus some other explanations / mentions that were missing.
68 lines
3.3 KiB
ReStructuredText
68 lines
3.3 KiB
ReStructuredText
.. _faq:
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.. include:: global.rst.inc
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Frequently asked questions
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==========================
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Which platforms are supported?
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Currently Linux, FreeBSD and MacOS X are supported.
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Can I backup VM disk images?
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Yes, the :ref:`deduplication <deduplication_def>` technique used by |project_name|
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makes sure only the modified parts of the file are stored.
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Can I backup from multiple servers into a single repository?
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Yes, but in order for the deduplication used by Borg to work, it
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needs to keep a local cache containing checksums of all file
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chunks already stored in the repository. This cache is stored in
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``~/.cache/borg/``. If Borg detects that a repository has been
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modified since the local cache was updated it will need to rebuild
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the cache. This rebuild can be quite time consuming.
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So, yes it's possible. But it will be most efficient if a single
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repository is only modified from one place. Also keep in mind that
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Borg will keep an exclusive lock on the repository while creating
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or deleting archives, which may make *simultaneous* backups fail.
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Which file types, attributes, etc. are preserved?
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* Directories
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* Regular files
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* Hardlinks (considering all files in the same archive)
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* Symlinks (stored as symlink, the symlink is not followed)
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* Character and block device files
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* FIFOs ("named pipes")
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* Name
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* Contents
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* Time of last modification (nanosecond precision with Python >= 3.3)
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* User ID of owner
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* Group ID of owner
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* Unix Mode/Permissions (u/g/o permissions, suid, sgid, sticky)
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* Extended Attributes (xattrs)
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* Access Control Lists (ACL_) on Linux, OS X and FreeBSD
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* BSD flags on OS X and FreeBSD
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Which file types, attributes, etc. are *not* preserved?
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* UNIX domain sockets (because it does not make sense - they are meaningless
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without the running process that created them and the process needs to
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recreate them in any case). So, don't panic if your backup misses a UDS!
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* The precise on-disk representation of the holes in a sparse file.
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Archive creation has no special support for sparse files, holes are
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backed up up as (deduplicated and compressed) runs of zero bytes.
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Archive extraction has optional support to extract all-zero chunks as
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holes in a sparse file.
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How can I specify the encryption passphrase programmatically?
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The encryption passphrase can be specified programmatically using the
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`BORG_PASSPHRASE` environment variable. This is convenient when setting up
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automated encrypted backups. Another option is to use
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key file based encryption with a blank passphrase. See
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:ref:`encrypted_repos` for more details.
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When backing up to remote servers, is data encrypted before leaving the local machine, or do I have to trust that the remote server isn't malicious?
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Yes, everything is encrypted before leaving the local machine.
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If a backup stops mid-way, does the already-backed-up data stay there? I.e. does Borg resume backups?
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Yes, during a backup a special checkpoint archive named ``<archive-name>.checkpoint`` is saved every 5 minutes
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containing all the data backed-up until that point. This means that at most 5 minutes worth of data needs to be
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retransmitted if a backup needs to be restarted.
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