On 20 September 2017 at 21:09, steve-ALUG@hst.me.uk wrote:
SD Card copier, described here: https://www.raspberrypi.org/blog/another-update-raspbian/
OK, that looks like the one I had looked at.
The SD Card copier can and does create an image suitable for the media you are copying too. [...] If you work out how much actual space is used and create the "fake drive" of just that size plus a bit of leeway, then you, create a minimal-ish backup.
That's a thought, although calculating that minimum size wouldn't be easy would it? (It's not just how much space is used on the disk, unless the sectors have been used consecutively.)
You say above that sd-sd copying doesn't lend itself to keeping backups. I respectfully disagree.
If you want a faithful bit-copy then that's fine, but how do you adapt the image approach to not include (for example) log or temporary files?
Hmm, once set up, the backuppc pi backup is quick, reliable and only backs up what you want it to, and what has changed.
If what I wanted was rolling backups of a live system that would make sense, but what I'm after are snapshots that I can use to "clone" the SD card, and when I say "I" I also mean other people if needed.
I think the problem is in how I framed the original post. My objectives are: - To have something I run offline (not from the Pi). I need to be able to clone multiple cards etc without having a Pi up and running. (As an aside, that also means I can do the work on a USB3 port on my desktop which speeds things up.) - For the backups to be as small as possible and not include irrelevant files (eg logs) - For backups and restores to be as fast as possible. In particular, not reading from/writing to unused parts of the SD cards - For backup files to be "accessible", in that it is as trivial as possible to extract files from them, compare backups etc. - For the backup/restore process to be self contained (not needing other tools) so that other people can use it with minimal overhead.
As an aside, I mentioned yesterday that I should have used Python for cross-platform, forgetting that 90% of what the script does is calling external tools like mkfs.ext4 which aren't going to be present on a non-Linux system. Doh!