How to make a block-level incremental backup using LVM?

[Fernando Lozano]

Hi there,

After evaluating a lot of backup solutions my employee, a small company, 
all of them very too expensive, I was wondering about the effort to 
emulate the workings of a "modern" backup solution using free software 
tools under Fedora Linux, CentOS and RHEL.

We already have a few TB on file shares (Samba) and mailboxes (Zimba) 
and just moving those bits around for our weekly full backup is proving 
to be too slow for our Gb network and impossible for the hosted machines 
we use as contingency and off-site backup . Beisdes, incremental backups 
are taking a too long time just scanning the file systems searching for 
changed files.

It looks Commvault, EMC, Symantec, etc are focusing block-level backups: 
copy used disk blocks for full backups and changed disk blocks for 
incremental ones. It looks they can get this information from many 
storage appliances, hypervisors and server OSes, but most focus on 
Windows Server, Exchange, Oracle, Sharepoint and big bucks storage 
appliances. Some of then talk about "continuous, forever incremental". 
We even have a few Windows servers, a small Oracle Standard database, 
and are evaluating am entry level storage, but for now one the big 
problem are our Linux file and mail servers and all proposals from 
vendors loooks like overfeatured and overpriced.

We already evaluated Amanda and Bacula. Setup looks too complicated, 
managing and monitoring looks low-level (the boss wants some dashboard 
like we already have from Zabbix). But worse, it looks like they will 
have the same problems as our current backup scripts based on tar, gzip, 
scp and rsync.

Sory for the long story, the question: could I implement block-level 
backups using dump, dd, and some LVM or ext utility? Maybe using 
inotify? Why no open source backup tool seems to be doing this?

Would any option allow me to restore an individual file? (I guess we can 
live with restoring entire file systems, it's just a matter of 
segregating a few file trees instead of having everything on the same 
logical volume.)

And maybe there is some open source solution or help to implement file 
archiving (moving old/unused files to a different volume so I can't 
forget about then on the daily backup).


[]s, Fernando Lozano