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Ok, I now have a new version that I've just finished testing to my satisfaction and I'll shortly be submitting it for consideration if anyone is interested

2 New Features:

  • Rotation Scheme
  • Backup Now

'Rotation scheme'. I've discovered to my cost that the current version is seriously flawed and I lost some important emails as I experienced a disk corruption that was then backed up(!) and I was unable to recover. It's this that prompted me to do something about it. The file being backed up was a VM; the VM's disk was corrupted as a result of the recent power fluctuations/sudden outage during the recent storms hitting the UK and I didn't discover the problem until the following morning by which time it was too late to do anything about it.
The scheme (in the absence of a .config file) defaults to 3 (grandfather/father/son), but selectable up to 7 (dailies). 'Disabled' and '1 backup' are effectively the same as the single backup that is the current (potentially fatal!) scheme.

NB: It's up to the user to make sure the USB target has enough space to hold the scheme selected .. +1 .. for the new archive!

'Backup now' - something I've wanted for a while.

So who's interested?
Tuesday, March 03 2020, 10:40 AM
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  • Accepted Answer

    Tuesday, March 03 2020, 12:09 PM - #Permalink
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    Interesting idea. I'd have thought the safest update would be to keep the existing backup methodology for existing installs but have the rotating methodology for new installs.

    When you start keeping multiple copies,of files the "tar" methodology becomes questionable as you end up with a full backup in each tar file. An alternative is to switch to rsync with the --link-dest= option. You lose on file compression, but you gain on not backing up unchanged files.
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    Tuesday, March 03 2020, 12:57 PM - #Permalink
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    That however, doesn't stack with the concept of grandfather/father/son - that methodology is to delete grandfather and replace it with father, and father with son. The new archive becomes the new 'son'. What you're describing is incremental backups and relies on the (eg) son being in place for (eg) a week and the incrementals being created on top of that, and then restarted when the changeover (son->father) occurs. I've not bothered with that (too much work!) and just a) left the daily backups being the gf/f/s cycle, with the option of extending that to 7 days.

    I can quite see that your option could be implemented for home/flexsaves, but configuration not so much (not worth it). I was just creating something of (basically) minimal change, but with the ability to have some form of protection from the single backup corruption - which is the danger as it stands. The update incidentally, won't affect existing installations as the backup that's in place when the update is put in place just becomes the 'father' when the next backup runs, then the gf, and then deleted (assuming the rotation scheme is left at the default).
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  • Accepted Answer

    Tuesday, March 03 2020, 01:07 PM - #Permalink
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    BTW - it is possible to create incrementals using tar and it's something I may now start looking at if I've got time.
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  • Accepted Answer

    Tuesday, March 03 2020, 03:45 PM - #Permalink
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    rsync is cleverer that that. If the file already exists in the earlier backup, it creates a hardlink to the same file in the new backup so it appears to be in both backups at the same time. The file only gets deleted when no hardlinks point to it.
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