Re: Tarsnap GUI shows 0 data archived or backed up

[Scott Robison <scott@casaderobison.com>]

On Thu, Sep 7, 2017 at 11:55 AM, Garance AE Drosehn
<gadcode@earthlink.net> wrote:
>
>> On Sep 7, 2017, at 4:21 AM, amar@sdf.org wrote:
>>
>>> So, can I make it smaller than 1.07 GB? Am I doing something wrong? I can
>>> explain what kind data are part of those 1.45 GB (can give a breakup too
>>> if needed).
>>>
>>> Can I compress it more, make de-duplication more aggressive? I have used
>>> the default config that came with the app.
>>
>> Or should I ask it in a separate thread? Or rather shoot a mail to Tarsnap
>> support? (But I see Graham is CCed in this mail thread).
>>
>> Thanks.
>
> There is one thing to note about de-duplication in tarsnap, compared to some other services.  Tarsnap can only de-duplicate across the files *you* are backing up, on a single specific machine you are backing up.  This is a side-effect of all the privacy and encryption that tarsnap guarantees.
>
> De-duplication works great in some other situations because the other service is de-duplicating files across (say) 20 different Windows machines.  So the first machine may use up 10-gig of space, but all of the rest of the machines might have less than a gig of additional unique files per machine.  Tarsnap cannot do that kind of optimization across multiple machines.

Depending on just how paranoid you are, and how disciplined you are,
you can have multiple machines deduplicate to a common store, as long
as you only have one running at a time.

What you wrote does not preclude that from happening, I just wanted to
point it out in case others might be interested in something like
that.

-- 
Scott Robison