Having a RAID is a great step towards keeping your data safe. A RAID-5 can provide you fast access to your data and the ability to survive and recover from a single drive failure without data loss. However, it’s always possible that you might accidentally delete a file or, even less likely, that your could have a single drive failure and then a second failure during RAID reconstruction. In order to protect against this, the TS-439 provides a few ways to backup your data.
I chose to attach a spare 1 TiB external drive to one of the rear eSATA ports. This allows the NAS to copy or synchronize selected shares to the external drive. Copy will do a full copy of the shares to the external drive. Synchronize will make the external drive share match that on the NAS by copying or deleting only what’s changed. I’ve chosen to synchronize my Archives (old photos and files) and my working laptop backups.
The synchronization process is very easy to setup and pretty fast. I’ve only had one problem with the backup process that won’t bother most people. My laptop backups are created using many hard-links, which allow multiple files to point to the same data so that copies of identical files take up less space. The synchronization performed by the QNAP TS-439 doesn’t duplicate these hard-links and causes the backup to be almost 3 times larger than the files stored on the NAS. If you see this kind of behavior, you’ll know why.