rsync a Quick Introduction

A great tool to mirror directories

JD P

Algoloma Systems

My Knowledge About Rsync

• Pretty Basic Use

• Mirror directories on the same box

• Mirror directories between different machines

• Pull and Push between servers

• ssh tunnels by default for remote connections

• Cross Platform

• Issues with larger files, YMMV

Directory Mirrors

• rsync will easily mirror directories

 rsync -avz source_directory target_directory 

On the same machine, it doesn't do file differencing by default.

This impacts expected performance.

• Use the -c, checksum, option to prevent that

Simple Example

 rsync -avz /etc/ /backups/romulus/etc 

• archive

• verbose

• use compression

Trailing Slashes

Trailing Slashes are critical

Use a slash to avoid confusion

Local Mirror Example

 

#!/bin/sh

EXCLUDES=/var/www/rsync_excludes

OPTS="-v -u -a --delete --links --recursive --stats --progress --exclude-from=$EXCLUDES "

BACKDIR="/var/www"

TARGET="/backups/romulus/"

mkdir -p ${TARGET}

rsync ${OPTS} ${BACKDIR} ${TARGET} 

Remote Mirror Example

TARGET="userid@server:/backups"

rsync ${OPTS} ${BACKDIR} ${TARGET} 

• Uses ssh by default

• Uses ~/.ssh/config so ports, userids, servernames can be managed easier

• userid can be left off if it matches the current machine or

• if settings from ~/.ssh/config are used

Rsync Backup Checklist

• Automatic & Easy? Yes

• Fast - incremental+? Yes if to different system

• Efficient - compressed? No, just the transfers are efficient

• Secure / encrypted? Yes ssh to cryptfs, truecrypt

• Versioned / not simple mirror? No

• Stored Remotely? Yes excells at this

• Restoration Verified? Yes

Rsync Uses

• No versioning

• Not a suitable general backup tool

• Great to push other backups to remote locations

• Great to backup large files that do not change (videos, music)

• Bad for large files that change (virtual machines)

Learn More

• rsync.samba.org

• Examples

• Central backup server w/ 7 day incrementals
• backup to a spare disk
• automatic backup at home
• Remote file lists

• man rsync

Questions?

• email: jdp (at) algoloma [dot] com
• Website: http://algoloma.com
• Blog: http://blog.jdpfu.com