[tahoe-dev] Proposed short description of tahoe-LAFS for personal backup

[Greg Troxel]

Saint Germain <saintger at gmail.com> writes:

> tahoe-LAFS is not really a backup software but rather a storage
> solution. The primary objective is to secure your data, either for

I would call it "distributed filesystem" rather than "storage solution".
(Choice of nerdy rather than buzzword terms.)

> privacy or for safety (against damage). To do so, it stores your

loss, rather than damage.  That may be a translation issue, but in
English I'd say loss because the emphasis is on servers that vanish more
than servers that have your file but have corrupted bits.

> encrypted data (encrypted at the source) on several machines organized
> in a network with a configurable policy (specifying K=2 and N=5 for
> instance, will spread your data on 5 machines, 2 of which need at least
> to be available to access your data).
>
> A few remarkable points:
>   - I like its "paranoid" approach. The idea is to trust no one (and
>     especially not your online storage provider)
>   - Don't need any redundant PAR2 checksum, given that the data are
>     duplicated and spread on the network (I however recommend to make
>     another backup on another media from times to times)

To protect against bad blocks, a filesystem with ecc might make sense,
but failures are often whole-disk.   So I don't disagree with you, but
"need" makes this seem black and white, whereas really we're talking
about probabilities.

Also, while tahoe works well, I don't think anyone thinks it is
reasonable to keep data only in tahoe.  This is especially true if one
enables expiration.

>   - Community et mailing-list are very active and very helpful (post a
>     message to see how welcoming they are !)
>   - Documentation is excellent
>   - You can join an already existing network (like VolunteerGrid2) by
>     adding your machine. That way all members of the network will have
>     access to a part of your (encrypted !) data et vice versa. It is
>     quite a psychological jump to accept (you have to trust encryption).
>   - You can also rent storage nodes to Least Authority Enterprises
>   - No delta encoding but has deduplication at the source, however only
>     on a file level.
>   - Works on Linux, Mac OS X and Windows. I have however a few doubts
>     on the Windows compatibility for managing locked files. But you can
>     use Duplicati which uses Windows VSS and can use tahoe-LAFS as
>     backend.

It also works fine on NetBSD.  It probably works on other BSDs.

I don't know what you mean about locked files.  If you mean locking like
in NFS and lockd/statd, then I wouldn't expect that to work anywhere.

>   - In case of backup interruption, resume is possible but you have to
>     upload the whole file again.
>   - Encryption is with AES-128 (soon to be combined with XSalsa20)
>
>
> I would be very interested to have any comment. But please be aware
> that I have to keep it quite short and simple.
> Sorry for the bad translation from french !
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