

Ask HN: Is there a good, zero-knowledge backup and synchronisation program? - StavrosK

Hi HN,
like everyone else, I need a good program that will backup and synchronise my files across computers. I don't trust Dropbox with all my data, so I came across SpiderOak and paid for a yearly account.<p>However, SpiderOak takes up 100% of my CPU for minutes on end, regularly freezes in some states, and a few days ago it stopped working altogether (it refuses to synchronise, it just sits there taking up all my CPU and even my attempts to reinstall it have been thwarted as it freezes on "Downloading data").<p>Is there a <i>reliable</i>, zero-knowledge program that will backup and synchronise data across computers? It's something indispensable but I'm disappointed with how buggy SpiderOak is, and all the alternatives I've seen are either backup-only or not zero-knowledge...<p>I'd appreciate any help!
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srjk
I've used unison in the past and liked it. May not fulfill the "zero
knowledge" criteria but IIRC it's fairly simple to set up.

<http://www.cis.upenn.edu/~bcpierce/unison/>

~~~
StavrosK
Unison does fulfill the zero-knowledge criteria, but it's not a daemon that
runs constantly, although I might give it a shot, thank you.

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jrsmith1279
You might look at Egnyte or Jungle Disk. We've used Egnyte for a few of our
clients and had mixed results with reliability. Luckily they give you a 30 day
trial, so you can try it out. Their pricing is also pretty decent.

~~~
StavrosK
Thank you, both of those look good. Your comment reminded me of AeroFS, a
synchronisation program that's peer to peer. I should give that a shot too, as
it doesn't need to be zero-knowledge if nobody other than my computers see my
data...

~~~
aquark
I've been running the AeroFS beta for a couple of weeks and am very happy with
it.

Nothing high volume or stressful, but it has done what it said it would
quickly and efficiently, and the client even worked behind the moderately
aggressive filters we have at work.

~~~
StavrosK
I just installed it, apart from the fact that it gave me an "AeroFS Drive" I
can't remove (I suspect the older version installed this but the new one
deprecated it) and the fact that I can't sync any two arbitrary folders, it
looks perfect.

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wladimir
I use Duplicity for remote incremental encrypted backups.

<http://duplicity.nongnu.org/>

It fulfills the "zero-knowledge" and reliable criteria. It's based on rsync.
I'm not sure whether you can use it for synchronisation, though, never tried
that.

~~~
StavrosK
I use duplicity+S3 as well for backups, it's the best for that. Hmm, I might
sync everything to my home NAS and back it up to S3 with duplicity, now that
you mentioned it, it might actually be cheaper.

Thanks!

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sidmitra
Also any of these cloud backups solutions available, that run on Ubuntu?

i know of Ubuntu One, wondering if there're cheaper/better alternatives.

~~~
StavrosK
Oh, yes, I forgot to mention, I run Ubuntu so that's a pretty big prerequisite
:)

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JoachimSchipper
Any reason you can't use truecrypt/whatever your favourite OS provides on top
of Dropbox?

~~~
StavrosK
Yes, Dropbox will have to up/download the entire multi-gigabyte file container
each time, as far as I know.

~~~
JoachimSchipper
I'm pretty sure that Dropbox uses [EDIT: was "something like the rsync
algorithm."] something like Tarsnap's algorithm: break a file into data-
dependent blocks and upload all changed blocks (optionally with rsync). (For a
toy implementation, let everything between two NUL bytes be a "block" - you
see how this is a big win for detecting changes and deduplication.) This is
supported by e.g. [http://serverfault.com/questions/52861/how-does-dropbox-
vers...](http://serverfault.com/questions/52861/how-does-dropbox-version-
upload-large-files).

TrueCrypt and alternatives definitely make sure that writing one unencrypted
sector only changes one encrypted sector worth of data - compare their
performance with gpg'ing the entire disk on each write, and you'll quickly see
why.

~~~
StavrosK
Hmm, I will have to look into that, although I think that Dropbox only does
per-file diffing... Thanks for the recommendation.

EDIT: Interesting, that makes the TrueCrypt suggestion not only viable, but
desirable. Thank you.

