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.