Hot Copy creates an instant point-in-time snapshot of any block device while the system is running without interrupting applications or requiring the use of LVM. As block level changes are made to the real device, hot copy makes a backup copy of the changed block. The changed blocks are efficiently stored in unused space on your hard disk. These stored changed blocks maintain a point-in-time snapshot and space is only needed when you make changes to the real device. You can even write to your snapshots.
The dsnapshot script provides a high-level interface to the Linux Logical Volume Manager. It uses its block-level snapshot support to create directory snapshots. In contrast to block-level snapshots, directory snapshots resemble the file system layer. Thus, you can snapshot any directory that is on a logical volume without worrying about the actual logical volumes, mount points, and paths.
Openduckbill is a simple command line backup tool for Linux. It is capable of monitoring files and directories marked for backup for any changes, and transferring these changes either to a local backup directory, a remote NFS exported partition, or a remote SSH server using rsync. It can either maintain an exact copy of the source at the backup destination, or maintain both current and previous versions of the source at the backup destination.
Lsyncd watches a local directory tree's event monitor interface (inotify). It aggregates and combines events for a few seconds and then spawns one (or more) process(es) to synchronize the changes. By default, this synchronization is done with rsync. Lsyncd is thus a lightweight live mirror solution that is comparatively easy to install. It does not require new filesystems or block devices and does not hamper local filesystem performance.
The Zumastor Linux storage project adds enterprise storage features to Linux, primarily improved snapshots and remote replication. Point-in-time, near zero-cost, block level snapshots can be added to any existing filesystem and performance does not degrade with multiple snapshots. Remote replication is achieved by sending minimal block level deltas between snapshots without having to traverse the entire filesystem like rsync does.
DIASER is a cloud storage class combined geo-data replication, long-term archive system, and WAN vault application. Manage long term mixed data archives generated by existing backup software. Ensure availability using commodity hardware. Retain administrative and financial control. It combines a disk-based backup volume management system and triple redundancy with a storage architecture designed to structure months to years of long term sustainable archiving space. It is a quick and low-cost way to make an environment more robust by backing up data in multiple places. This replication also provides fast retrieval of archived data from all node hosting locations. A Perl installer creates the system. Nodes can be dedicated to storage or used for existing services over unused bandwidth. DIASER works in user space over SSH.