Changing HDDs in Synology DS418: Adding Another Synology NAS

Replacing hard drives in a Synology DS418 and integrating a second NAS requires careful planning to maintain data integrity. This guide outlines the safe removal of existing drives, the installation of new storage media, and the configuration of replication tasks between your primary unit and an additional Synology device to expand capacity securely.

Preparing for Hardware Replacement

Before touching any hardware, you must ensure that your data is safe. If you are replacing drives due to failure or upgrade, verify that your current RAID volume status is healthy. Navigate to Storage Manager in the DSM interface and check the health status of each disk. If you plan to add a second NAS later, ensure both units are running compatible versions of DSM to facilitate smooth replication setup. Always back up critical data to an external location before proceeding with physical changes.

Safely Removing Existing Hard Drives

Synology NAS devices support hot-swapping, but it is best practice to shut down the system if you are unsure about drive compatibility or if the drives are part of a SHR (Synology Hybrid RAID) or RAID 5/6 array that requires reconfiguration.

1. Shut Down the System: Go to the main menu, select Power, and choose Shut Down. Wait for the power LED to stop blinking.
2. Eject the Drive Tray: Press the small eject button on the drive tray handle. The tray will pop out slightly. Pull it fully out of the bay.
3. Remove the Drive: Unscrew the four screws securing the hard drive to the tray. Carefully lift the drive out. If you are reusing the trays, label them to remember their original positions, especially if you are moving to a different RAID level.

For more details on troubleshooting issues where drives are not recognized after such operations, refer to our article on Troubleshooting NAS Build: HDDs Not Working.

Installing New Hard Drives

Once the old drives are removed, prepare your new hard drives. Ensure they are compatible with the DS418’s SATA III ports. It is recommended to use drives specifically marked as "NAS" class, such as WD Red Plus or Seagate IronWolf, as they are optimized for the vibration and heat profiles of network-attached storage environments.

1. Mount the Drives: Place the new hard drives into the empty drive trays. Align the screw holes and secure them tightly. Do not overtighten, as this can damage the drive casing.
2. Insert into Bays: Slide each tray back into its respective bay until it clicks into place. Ensure all four bays are populated if you are initializing a full volume.
3. Power On: Turn on the DS418. The system will detect the new drives. You may see a notification in the Notification Center indicating that new disks have been detected.

Creating or Expanding Storage Volumes

With the new drives installed, you need to create a storage pool and volume. Open Storage Manager from the main menu.

• Create Storage Pool: Click on Create under the Storage Pool section. Select the type of RAID you wish to use (e.g., RAID 5 for balance of speed and redundancy). Follow the wizard to initialize the pool.
• Create Volume: Once the pool is created, proceed to create a volume. Choose the file system type; Btrfs is recommended for newer features like snapshotting and compression.

If you encounter encryption requirements for sensitive data during this phase, consider reviewing strategies for Preventing Data Loss in NAS Storage to ensure your new volume is protected against unauthorized access.

Adding a Second Synology NAS for Expansion

To expand your storage capacity beyond the physical limits of the DS418, you can integrate a second Synology NAS. This is typically done using Hyper Backup for offsite replication or Active Backup for Business for server protection. However, for seamless storage expansion, you might look into Link Aggregation or specific replication tools provided by Synology.

1. Network Connection: Connect both NAS units to the same network. For higher throughput, consider connecting them via a dedicated switch or using the eSATA ports if available on older models (note: DS418 does not have eSATA, so rely on Gigabit Ethernet).
2. Configure Replication: On the primary DS418, open Hyper Backup. Create a new backup task and select the destination as the second NAS. This allows you to store copies of your data on the secondary unit.
3. Accessing Remote Data: While this does not merge the drives into one logical volume, it effectively expands your total usable storage footprint across two devices. Ensure both devices have static IP addresses for stable connections.

This approach avoids the complexity of managing multiple RAID arrays simultaneously, which can be risky. For insights on managing multiple storage configurations safely, see Can I swap between two RAIDs on one NAS?.

Final Checks

After setting up the new drives and the secondary NAS, run a SMART test on all drives to ensure they are functioning correctly. Monitor the system health dashboard for any warnings. Regularly update the firmware on both NAS units to benefit from the latest security patches and performance improvements. Remember that safe removal practices apply to USB peripherals as well; always follow proper procedures to avoid corruption, as detailed in our guide on Do USB Pendrives Really Need a Safe Removal?.

Frequently Asked Questions

Can I mix old and new hard drives in the same RAID array?

It is strongly discouraged to mix drives of different capacities, speeds, or ages within the same RAID array. This can lead to performance bottlenecks and increased risk of failure if the older drives fail prematurely. Always replace all drives in a RAID set with identical specifications for optimal stability.

Will my data be lost when I replace the hard drives?

Yes, replacing hard drives in a RAID configuration will result in data loss unless you perform a migration or backup first. If you are upgrading to larger drives, you must back up your data externally, recreate the volume with the new drives, and then restore your files. Never attempt to replace drives without a verified backup.

How do I connect the second NAS to the first one securely?

The most secure method is to use Synology’s native replication tools like Hyper Backup over your local network. Ensure both devices are on the same subnet and use strong passwords for the administrative accounts on both units. Avoid exposing these replication services directly to the internet without proper firewall rules and VPN access.

What happens if I insert a drive that is already formatted?

If you insert a drive that contains a previous RAID structure or volume, DSM will prompt you to either initialize the drive or delete the existing data. If you want to preserve data on that specific drive, do not initialize it. Instead, mount it as an external drive or use it for a separate backup task. Initialization will erase all data on that drive.

Is it better to use RAID 5 or RAID 6 for the DS418?

RAID 6 is generally safer for a 4-bay NAS because it can withstand the simultaneous failure of two drives. RAID 5 can only tolerate one drive failure. Given that rebuilding a large RAID 5 array takes time and puts stress on the remaining drives, RAID 6 offers better protection against data loss during rebuilds, albeit with slightly less usable space.