[Discuss] On-site backups revisited - rsnapshot vs. CrashPlan

[richb at pioneer.ci.net (Rich Braun)]

I wrote last month a query about CrashPlan free peer-to-peer software from
Code42.  I failed to get satisfaction from the vendor, even though the CEO of
Code42 made a response, you can view the thread at
https://crashplan.zendesk.com/entries/64160-How-do-I-request-a-full-integrity-check
; he didn't follow up any further though.

I am developing an alternative strategy based on suggestions from BLU.  Here's
what I posted at the CrashPlan forum about that:

I haven't yet found a suitable replacement for CrashPlan (peer-to-peer) off
the shelf, but here's the strategy I'm using going forward:

* Set up a central backup server using rsnapshot which can easily
  be set up to make incremental filesystem backups similar to
  CrashPlan's peer-to-peer mechanism
* Supplement rsnapshot with a script to make sha256sum checksums of
  the archive contents, stored in a simple db table
* Craft a monitoring script to warn me in case the archive files no
  longer match checksums, and to warn when backups are incomplete
  or stale
* Make a tool that makes it more obvious to me whether a given local
  directory or computer is being backed up

That's all I really wanted CrashPlan's peer-to-peer software to do, but it's
hard to find out what it's actually doing under the covers.  For on-site
backups, I don't need some of the other features that CrashPlan provides: 
encryption, de-duplication, the convenient UI.  But I do urgently need
monitoring that goes beyond CrashPlan's weekly status emails, along with
integrity checks that I control and understand.

I /think/ I'm still happy with the paid remote-site backup service but I have
to supplement or replace my local backups as noted above.

---
I'm not sure how aggressive I have to be with the integrity checking -- I've
actually never had a known instance of a file getting corrupt -- but I figure
it's worthwhile for a long-term archive.  Have any of you found or developed
tools for this part of it, in particular doing it in conjunction with
rsnapshot or another similar tool?

Setting up rsnapshot is fairly easy, though at some point I want to write up
and post a better how-to for the benefit of future users.  In particular the
two-step process of "sync" and "rotate" isn't well-documented in the places I
looked online, and you really want to have a separate script (beyond what cron
does by itself) to invoke the rotation methods.

-rich