[NCLUG] I think

[Luke Jones]

I didn't have a (real) keyboard yesterday so I didn't say much but for
something as important as doing backups, it's worth the effort to
include traps:

http://www.tldp.org/LDP/Bash-Beginners-Guide/html/sect_12_02.html

For a trivial shell script, why bother, but for scripts you're going
to depend on, it's worth the extra effort. You can clean up your work
on any kind of interrupt and, more importantly, you can know that your
work didn't get done.


On Fri, Feb 21, 2014 at 9:55 AM, Zak Smith <zak at computer.org> wrote:
> On Fri, Feb 21, 2014 at 09:26:40AM -0700, Stephen Warren wrote:
>> I'd suggest simply copying the whole tree with rsync, to a separate
>> (dated) backup tree. That way, you can easily do something like:
> ..
>> As an extension to this technique, you can then hard-link your backup
>> trees together, so you can keep N backups in the space of 1 backup,
>> ignoring effects due to actual changes to the files. Of course, you need
>> some code to prune old backups so that the backup sizes don't grow in an
>> unbounded fashion if your files keep changing.
>>
>> rsnapshot appears to be a tool to automate this. IIRC, I derived my
>
> The cool thing about doing this is rsync's "--link-dest" feature (ie,
> you give --link-dest=<the most recent snapshot directory>).  This does
> not use storage for all the files that have not changed.   rsnapshot
> is a wrapper around rsync that is based on this feature.  The downside
> of this is if you get one screwed-up snapshot directory, you may lose
> the "hard link" continuity, ie, if you had the backups
>
> 20140101 - original backup
> 20140201 - next backup, links non changed files back to 20140101
> 20140301 - this one is partially screwed up becasue of a power failureor something
> 20140401 - this one will duplicate the data instead of re-using via
>    hardlinkes from 20140201 (20140101) for files that are missing in
>    20140301.
>
> Another alternative is to run ZFS with snapshotting on your
> destination rsync volume.  Or run it on your primary volumes (but this
> is not a "backup" more like version control).
>
>
>
>
> --
> # Zak Smith    mobile 970-232-4468
>
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-- 
Luke Jones  slukejones at gmail.com (828) 6-SLUKEJ