QNAP to Synology
The rsync setups on the Synology and QNAP NASes are similar, but each has features that the other doesn't. QNAP refers to its NAS-to-NAS backup feature as Remote Replication, which is found under the System Tools menu. Figure 4 shows the controls, which include separate enables for rsync serving and target and the ability to change the default rsync port number. (Synology provides only an rsync enable.)
Figure 4: QNAP Remote replication (rsync)
Clicking the New button brings up the Add a remote replication job screen (Figure 5). I selected Rsync server as the Server type instead of NAS server, which is used for QNAP NAS targets.
Figure 5: Backup to Synology settings
The Destination Path (Network Share/Directory) setting name is misleading and the online help text doesn't make clear that you can't just enter just any share name here. Whatever you enter has to be an rsync module name. Since Synology has set the module name as NetBackup, that's what I had to enter. But I could create a new subfolder (qnap_bkup) in the NetBackup directory to keep the backup files separate from my NV+ test backup.
Like Synology, QNAP requires using a username and password to access the target folder. But I didn't have to create a user to set access permissions. Instead, I just used the default admin user and password. Once I had entered all the Remote Destination settings, I clicked the Test button, which checks to see if a connection can be properly made to the rsync target. You get an error if it can't, but you don't get much information to help you determine why the connection failed.
I didn't want to set a backup schedule, but there isn't an option to just create and save a backup job, so I set a dummy schedule.
Both QNAP and Synology provide enables for incremental backup. But where enabling incremental backup on the Synology also will remove files deleted on the rsync source, QNAP provides a separate enable for this (Delete extra files on remote destination). The QNAP also lets you enable file compression to minimize bandwidth, where Synology provides a block-level backup option.
Once I saved the job on the QNAP, I had to go back and edit the job again to run it, since QNAP doesn't provide the equivalent of Synology's Back Up Now button on the backup job list page. The test run, which copied a 4.35 GB ripped DVD test folder that I use in the NAS Chart Vista SP1 file copy tests, had a throughput of 3.82 MB/s without compression—not very speedy.
I also tried a backup with compression enabled, but quit it after more than an hour has passed and it was still nowhere done. Since there is no user control to stop a backup job, I had to log in as admin via SSH and kill the rsync process.