rdiff-backup & rsync on some OS files

[aljames2]

I feel I should know this and may kick myself for not seeing it already.

Internals look like this:

Sata SSD (Ubuntu OS) ----> HDD-1 (rdiff-backup of SSD /home, /etc, etc.) ----> HDD-2 (rsync backup of HDD-1)

Ubuntu server runs on the SSD. I use LVM snapshots & rdiff-backup to backup daily /home, /etc, /usr/local to my HDD-1. Then I make a rsync backup of HDD-1 on HDD-2.

Question: I understand rdiff-backup is better at backing up OS files & versioning. I have read that rsync is not good for this because of the linking & metadata. Should I instead be using dd to make a mirror of HDD-1 on HDD-2 to better capture the permissions & other metadata? I do use rsync for data backups but not sure if I am messing up by using it to backup /home, /etc, usr/local on this 2nd (redundant) HDD-2.

[TheFu]

Nope. The rsync of the rdiff-backup area(s) will capture all the data, versions, and metadata you need ... assuming you use something like:

sudo ionice rsync -avz  $EXCLUDES    --delete     /1st-HDD/$HOSTNAME/      /2nd-HDD/$HOSTNAME/

Running as root matters, but only slightly. Doesn't really matter which variant of --delete you use. There are a few options. --delete-after would be the safest, but uses the most storage. --delete-before is the least safe, but uses the least storage for when the target is tight.

But perhaps you want to enable LUKS encryption for the disks or perhaps use a backup server over the network?

rsync behaves differently when it is locally attached compared to going over a network. Over a network, the librsync magic happens, unlike when it is used locally. There are rsync options which can force the network block comparisons to be used for local rsync tasks. I always have to hunt those down. rdiff-backup uses librsync with that comparison option always AND it retains the block checksum between runs, so it is much faster than straight rsync during comparisons.

The rsync manpage is a beast. Bet you learn something new. I always do, every time I open it up.

[aljames2]

Great thanks!! No joke, the manpage is a college course

[aljames2]

A few rsync options are confusing me -AX. -AX preserves ACLs, permissions, and extended attributes.

-avz works when pulling or pushing from the client machine:

rsync -avz --delete user@server:/home/ /home/ --dry-run
rsync -avz --delete /home/ user@server:/home/ -dry-run

But if I try to use the -AX options to preserve permissions, I run in to permission denied issues when I try to push to the server. I know I shouldn't push and better to pull but I haven't set up the ssh keys in the other direction yet.

rsync -aAXvz --delete /home/ user@server:/home/ --dry-run

Is -AX necessary as I don't see it being used in many examples?

In my examples here I use /home/ and would always pull when backing up, probably a bad example for what I'm actually doing. I am working on editing some scripts and document files saved in a small working directory and I am trying to push changes back to the server to keep the most current version on the server. It's sometimes easier to push these small changes but I should do it better. I digress