Alexander Leidinger

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Test­ing tarsnap

I am impressed. Yes, really. It seems tarsnap DTRT.

I made a test with tarsnap. I made a backup of some data (a full backup of every­thing is kept on a ZFS vol­ume on an exter­nal disk which is only attached to make a full backup once in a while) of one of my sys­tems. This data is 1.1 GB in size (most of it is /usr/src checked out via sub­ver­sion and extended with some patches — no music, pic­tures or other such data). This com­presses down to 325 MB. Of this 325 MB of data only 242 MB is stored encrypted on the tarsnap server (auto­matic de-duplication on the backup client). The sec­ond backup of the same data in the fol­low­ing night (again 1.1 GB in total, 325 MB com­pressed) caused 216 kB of new data to be stored on the tarsnap server (again, de-duplication on the client). What I have now are two full off-site back­ups of this data (two archives with 1.1 GB of data after decom­pres­sion), with the ben­e­fit that the addi­tional stor­age space required is the stor­age space of an incre­men­tal backup.

The cost (in dol­lar) of this so far is 0.074603634 for the ini­tial trans­fer of the data, 0.00242067783 for the data stor­age on the first day, plus 0.0019572486 for the trans­fer for the sec­ond backup. From the ini­tial 29.93 I still have 29.85 (rounded) left. If I fac­tor out the ini­tial trans­fer and assum­ing that the rate of change for this sys­tem stays con­stant, this comes down to 0.01 (rounded-up) per day for this sys­tem (or about 8 years of backup if I do not add more sys­tems and do not add more than the ini­tial 29.93 (= EUR 20) — and the price of this ser­vice does not increase, off course). Is this data worth 1 cent per day for me? Yes, for sure! Even more, but hey, you did not read this here. :)

That is what you get when a per­son designs a ser­vice which he is will­ing to use him­self for a price he wants to pay him­self (while still not lose money with the service).

Colin, again, I am impressed. Big thumbs up for you!

Now I just have to add some more sys­tems (/etc and sim­i­lar of var­i­ous jails… and of course the data of this blog) and pol­ish my tarsnap script for “peri­odic daily” .

P.S.: Yes there are also places to improve, I found already some things (the con­fig file parser is a lit­tle bit strict what it accepts, and some things should be more doc­u­mented) but Colin is respon­sive and open to improve­ment suggestions.

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One Response to “Test­ing tarsnap”

  1. Tarsnap usage statistics « The Daily BSD Says:

    […] Test­ing tarsnap […]

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