Package: omirr (0.3-4)

Online Mirror Daemon

Duplicates directory hierarchies between several machines. The omirr package consists of the online mirror daemon in.omirrd and a kernel patch. The daemon supports mirroring of directory hierarchies between several machines. It distributes files, file contents and file attributes to remote machines, comparable to the rdist(1) program, but it has several differences compared to rdist.

Firstly, it synchronizes the files online, usually immediately, using an interface to the local kernel which notifies the daemon about all file system modifications. This results in equivalent file system contents of the mirrored hierarchies on all machines. The daemon is started once, usually at boot time and then runs continuously. In contrast, the rdist program is started manually or from cron, then distributes its files and terminates.

Secondly, it allows symmetric mirroring. With rdist, one file system hierarchy is the master version used to update the others. The hierarchies synchronized by in.omirrd are all treated equally, i.e. there is no master copy. The file system modifications are time-stamped and in.omirrd uses the latest version of each file. This is the same as concurrently modifying the same file from two Unix processes: the last modification takes effect. But, since in.omirrd does not support file (or even record) locking, it should not be used for file system hierarchies with a lot of concurrent updates on several machines or for files usually accessed using locking mechanisms, like database files.

Thirdly, it can synchronize several remote machines concurrently. rdist updates multiple hosts sequentially.