[](http://isitmaintained.com/project/deajan/osync "Percentage of issues still open")
osync is a stateful synchronizer. This means it's agentless and doesn't have to monitor files for changes. Instead, it compares replica file lists between two runs.
A full run takes about 2 seconds on a local-local replication and about 7 seconds on a local-remote replication.
osync uses a initiator/target sync schema. It can sync local to local or local to remote directories. By definition, initiator replica is always a local directory on the system osync runs on.
osync uses pidlocks to prevent multiple concurrent sync processes on/to the same initiator/target replica.
Quick sync mode is convenient to do fast syncs between some directories. However, the [configuration file mode](#configuration-file-mode) gives much more functionality.
In order to run osync the quickest (without transferring file attributes, without softdeletion, without prior space checks and without remote connectivity checks, you may use the following:
If you intend to sync a remote directory, osync will need a pair of private/public RSA keys to perform remote SSH connections. Also, running sync as superuser requires to configure the `/etc/sudoers` file.
To display which files and attrs are actually synchronized and which files are to be soft deleted / are in conflict, use `--verbose` (you may mix it with `--silent` to output verbose input only in the log files):
Use `--no-maxtime` to disable execution time checks, which is usefull for big initial sync tasks that might take long time. Next runs should then only propagate changes and take much less time:
Once you're confident about your first runs, you may add osync as a cron task like the following in `/etc/crontab` which would run osync every 30 minutes:
Please note that this syntax works for RedHat/CentOS. On Debian you might want to remove the username (i.e. root) in order to make the crontab entry work.
You may want to sequentially run multiple sync sets between the same servers. In that case, `osync-batch.sh` is a nice tool that will run every osync conf file, and, if a task fails,
To run all `.conf` files found in `/etc/osync`, and retry 3 times every configuration that fails if the whole sequential run took less than 2 hours, use:
> Monitoring changes requires inotifywait command (`inotify-tools` package for most Linux distributions). BSD, macOS and Windows are not yet supported for this operation mode, unless you find an `inotify-tool` package on these OSes.
Monitor mode will perform a sync upon file operations on initiator replica. This can be a drawback on functionality versus scheduled mode because this mode only launches a sync task if there are file modifications on the initiator replica, without being able to monitor the target replica. Target replica changes are only synced when initiator replica changes occur, or when a given amount of time (600 seconds by default) passed without any changes on initiator replica.
To run this mode as a system service with the `osync-srv` script, you can run the `install.sh` script (which should work in most cases) or copy the files by hand:
When submitting a PR, please be sure to modify files in dev directory (`dev/n_osync.sh`, `dev/ofunctions.sh`, `dev/common_install.sh etc`) as most of the main files are generated via merge.sh.
