[clug] note on restoring incremental backups using rsync write-batch was Re: rsync question

[Brett Worth]

On 03/04/16 13:10, Steve Jenkin wrote:
> I want to backup partition images to an external disk, but wish to reduce the space used and only store incrementals.

Almost totally unrelated to your question...

I used to use rsnapshot for backups which would first do a cp -rl into a new directory 
then an rsync.  It was pretty good at space minimisation but if you made modifications to 
a file you would end up wit a new copy.  Suboptimal if those files are large (vm images).

Once zfs got stable I moved to that for my backup needs.

So now I have an rsync copy of all the machines that need to be backed up sitting on a zfs 
filesystem.  That filesystem has hourly, daily, weekly and monthly snapshots created using 
zfs-auto-snapshot: https://github.com/zfsonlinux/zfs-auto-snapshot

I then have cron jobs running rsync's from the various backup clients a couple of times a 
day.  If there's a couple of snapshots between rsync's it doesn't matter since no actual 
space is being used.  The rsync used must have the --inplace else you lose the 
copy-on-write advantage of zfs.

This has been working really well for the past three years though the drive I've been 
backing up to has bee switched out.  It's currently an 8TB seagate.

It also has the advantage of being able to time travel into the filesystems with a simple 
"cd /MOUNTPOINT/.zfs/snapshots" command.  A restore is just an scp or rsync back to the 
client.

Brett


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