rdiff-backup backs up one directory to another. The target directory ends up a copy of the source directory, but extra reverse diffs are stored in a special directory so you can still recover files lost some time ago. The idea is to combine the best features of a mirror and an incremental backup. rdiff-backup can also operate in a bandwidth- efficient manner over a pipe, like rsync. Thus you can use rdiff-backup and ssh to securely back up to a remote location, and only the differences will be transmitted. It can also handle symlinks, device files, permissions, ownership, etc., so it can be used on the entire file system.
changedfiles is a framework for filesystem replication, security monitoring, and/or automatic file transformations--essentially any application where you'd poll files or directories and either do something to them or send them somewhere else (or both). The difference is that the kernel tells you when they change instead of you having to poll. It's an easy real time FTP push mirror to one or multiple sites. It's also a full fledged MySQL client, so you can do realtime database operations (for example, batch imports). It consists of two parts: a kernel module (works with Linux kernel version 2.4) which reports to a device whenever a file on the filesystem changes, and a daemon which runs in user space and can be configured to do almost any action when a change to a file matching the one of the patterns it looks for is reported. The kernel module is SMP safe and has been tested on Intel, PowerPC, and Alpha.
fsbackup is an incremental backup creation utility. It supports backup compression and encryption. Backups can be stored on the local file system, and a remote host (via SSH, or FTP). Some additional scripts allow backup SQL tables from PostgreSQL and MySQL, save system configuration files, and a list of installed packages. Backed-up files can be recovered, and system packages can be reinstalled.
Radiant Data PeerFS is real-time peer-to-peer distributed replicating file system featuring global file and sectional locks. All read operations are performed locally, and only file changes are transmitted across the network. It supports databases such as MySQL, as well as images and documents. All nodes are active/active, allowing for load balancing. Clients can also be hot switched between nodes, eliminating downtime. It also supports AES encryption for use across the Internet.
Phrealon is a bootable Linux CD based on Slackware Linux 8.0, designed to allow the easy imaging of multiple workstations. It utilizes the updcast set of Linux tools to accomplish this. It provides an interface that allows users to select options from menus and autodetects most of the supported NICs.
ldapsync.pl is a simple Perl script that uses Net::LDAP to copy new and updated records to a second LDAP server. Although most LDAP servers offer some sort of replication facility, this approach allows the frequency of updates to be controlled. It can be used to copy information between LDAP servers in different security layers without the individual servers having permission to contact each other. It was developed using the SunONE Directory Server on Solaris 9.