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update / improve / reformat FAQ 

- reduce redundancy (platforms are documented in README.rst)
- reformat to 80 chars width
- clarify checkpoints
- remove workarounds for stuff that was fixed
This commit is contained in:
Thomas Waldmann 2015-09-30 17:13:22 +02:00
parent 6aca4694fe
commit ba5fa0ba99
1 changed files with 35 additions and 42 deletions
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docs/faq.rst
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@ -4,16 +4,9 @@
Frequently asked questions
==========================
Which platforms are supported?
Currently Linux, FreeBSD and MacOS X are supported.
OpenBSD and NetBSD work also, except for xattrs and ACLs.
You can try your luck on other POSIX-like systems, like Cygwin,
other BSDs, etc. but they are not officially supported.
Can I backup VM disk images?
Yes, the :ref:`deduplication <deduplication_def>` technique used by |project_name|
makes sure only the modified parts of the file are stored.
Yes, the :ref:`deduplication <deduplication_def>` technique used by
|project_name| makes sure only the modified parts of the file are stored.
Also, we have optional simple sparse file support for extract.
Can I backup from multiple servers into a single repository?
@ -47,9 +40,10 @@ Which file types, attributes, etc. are preserved?
* BSD flags on OS X and FreeBSD
Which file types, attributes, etc. are *not* preserved?
* UNIX domain sockets (because it does not make sense - they are meaningless
without the running process that created them and the process needs to
recreate them in any case). So, don't panic if your backup misses a UDS!
* UNIX domain sockets (because it does not make sense - they are
meaningless without the running process that created them and the process
needs to recreate them in any case). So, don't panic if your backup
misses a UDS!
* The precise on-disk representation of the holes in a sparse file.
Archive creation has no special support for sparse files, holes are
backed up as (deduplicated and compressed) runs of zero bytes.
@ -77,52 +71,51 @@ When backing up to remote servers, do I have to trust the remote server?
Yes, as an attacker with access to the remote server could delete (or
otherwise make unavailable) all your backups.
If a backup stops mid-way, does the already-backed-up data stay there? I.e. does |project_name| resume backups?
Yes, during a backup a special checkpoint archive named ``<archive-name>.checkpoint`` is saved every 5 minutes
containing all the data backed-up until that point. This means that at most 5 minutes worth of data needs to be
retransmitted if a backup needs to be restarted.
If a backup stops mid-way, does the already-backed-up data stay there?
Yes, |project_name| supports resuming backups.
During a backup a special checkpoint archive named ``<archive-name>.checkpoint``
is saved every checkpoint interval (the default value for this is 5
minutes) containing all the data backed-up until that point. This means
that at most <checkpoint interval> worth of data needs to be retransmitted
if a backup needs to be restarted.
Once your backup has finished successfully, you can delete all ``*.checkpoint``
archives.
If it crashes with a UnicodeError, what can I do?
Check if your encoding is set correctly. For most POSIX-like systems, try::
export LANG=en_US.UTF-8 # or similar, important is correct charset
I can't extract non-ascii filenames by giving them on the commandline on OS X!?
This is due to different ways to represent some characters in unicode.
HFS+ likes the decomposed form while the commandline seems to be the composed
form usually. If you run into that, for now maybe just try:
I can't extract non-ascii filenames by giving them on the commandline!?
This might be due to different ways to represent some characters in unicode
or due to other non-ascii encoding issues.
If you run into that, try this:
- avoiding the non-ascii characters on the commandline by e.g. extracting
- avoid the non-ascii characters on the commandline by e.g. extracting
the parent directory (or even everything)
- try to enter the composed form on the commandline
- mount the repo using FUSE and use some file manager
See issue #143 on the issue tracker for more about this.
If I want to run |project_name| on a ARM CPU older than ARM v6?
You need to enable the alignment trap handler to fixup misaligned accesses::
echo "2" > /proc/cpu/alignment
Can |project_name| add redundancy to the backup data to deal with hardware malfunction?
No, it can't. While that at first sounds like a good idea to defend against some
defect HDD sectors or SSD flash blocks, dealing with this in a reliable way needs a lot
of low-level storage layout information and control which we do not have (and also can't
get, even if we wanted).
No, it can't. While that at first sounds like a good idea to defend against
some defect HDD sectors or SSD flash blocks, dealing with this in a
reliable way needs a lot of low-level storage layout information and
control which we do not have (and also can't get, even if we wanted).
So, if you need that, consider RAID1 or a filesystem that offers redundant storage
or just make 2 backups to different locations / different hardware.
So, if you need that, consider RAID or a filesystem that offers redundant
storage or just make backups to different locations / different hardware.
See also `ticket 225 <https://github.com/borgbackup/borg/issues/225>`_.
Can |project_name| verify data integrity of a backup archive?
Yes, if you want to detect accidental data damage (like bit rot), use the ``check``
operation. It will notice corruption using CRCs and hashes.
If you want to be able to detect malicious tampering also, use a encrypted repo.
It will then be able to check using CRCs and HMACs.
Yes, if you want to detect accidental data damage (like bit rot), use the
``check`` operation. It will notice corruption using CRCs and hashes.
If you want to be able to detect malicious tampering also, use a encrypted
repo. It will then be able to check using CRCs and HMACs.
Why was Borg forked from Attic?
Borg was created in May 2015 in response to the difficulty of
getting new code or larger changes incorporated into Attic and
establishing a bigger developer community / more open development.
Borg was created in May 2015 in response to the difficulty of getting new
code or larger changes incorporated into Attic and establishing a bigger
developer community / more open development.
More details can be found in `ticket 217
<https://github.com/jborg/attic/issues/217>`_ that led to the fork.