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.