Synology: Disk Replacement on DSM 5

Synology feature image tile - blackI wanted to replace the drives in my older Synology 212J NAS which is running the new Diskstation Manager 5 beta software. Specifically, it’s running DSM 5-4418 Update 1. There was two Seagate Barracuda ST3000DM001 3TB drives and I was replacing them with Western Digital Red NAS drives, also 3 TB each.

Replacing hard drives is super-simple in a Synology NAS, even one without hot swappable drive bays. All that was needed was a Phillips #2 screwdriver.

My Synology DS212J has two 3TB drives configured to use Synology Hybrid Raid (SHR). With just two disks of the same size this is a mirrored volume similar to RAID 1.

To replace both disks they’ll have to be done one at a time, allowing the SHR to rebuild after the first drive. While no data *should* be lost it’s always a good idea to have backups that are current and known to be good before mucking with the drives. In addition, the replacement disks have to be the same size or larger than the existing drives.

It will take several hours to rebuild the volume once the drive is replaced. The Synology NAS will be usable but there might be a performance hit. I tend to do drive replacements in the evening to allow the rebuild to happen while I sleep.

Here’s the process (click any image to see it full size):

1. Logon to the Disk Station Manager (DSM) web interface and shut down the Synology.

screenshot showing the shutdown

Once the NAS shuts down it’s time to replace the drive.

2. Remove the two screws on the back of the NAS (other models may have different ways to open which doesn’t change the overall process). Once the screws are removed slide the two sides of the NAS apart so it opens.

Then open the unit and put the cover aside so you can get at the drives.

photo of the opened DS212J
The DS212J opened up. The Seagate drive will be replaced.

3. I’ll be replacing the Seagate drive which is on top. But it doesn’t need to be removed if you’re replacing the bottom drive. Remove the screws for the drive you’re replacing. Also note that the drives are labelled 1 and 2. While the new drive will be obvious in DSM, the number will match its number in DSM.

Once the screws are removed, slide the drive out. It may take a little force to slide it out of the connector but you’ll be fine if you pull it straight out along the rails.

4. Slide the new drive in along the rails so the SATA connector on the drive slides into the SATA connector in the NAS.

5. Then put the cover back on and fire up the Synology. Eventually you’ll hear a beep. This means DSM has detected a degraded volume. (Assuming you haven’t turned off the beeps.)

photo of the now re-disked Synology DS212J

6. Once the NAS finishes booting logon to the Diskstation Web Interface and start Storage Manager.

screenshot of opening the storage manager7. You’ll see the attention screen with the warning that a disk is degraded and needs to be replaced. The whole reason for the warning is that we just replaced the disk, so we’ll ignore the instructions.

screenshot of the Storage Manager alert8. If you want to confirm it’s the new disk that was bad select HDD/SSD in the left column to see which disk is bad. (But with two drives and a running NAS there really isn’t any other option.)

screenshot if the disk status screen
Our new drive isn’t initialized

9. Select Volume in the left column then click the Beep Off button to silence the alarm. Click the down arrow to show all the column information.

screenshot of the initial volume info screen
The SHR is degraded
screenshot of the expanded volume info screen
The new hard drive requires rebuilding the SHR

10. We can ignore the recommendation since the drive is already replaced. Click the Manage button to start the management wizard.  Select Repair which should be the default selection and click Next

screenshot of the disk maintenance wizard

Select the disk to add, which should be the default selection

screenshot of the disk maintenance wizard

Acknowledge the warning

screenshot of the disk maintenance wizard

11. Click the Apply button. Don’t be misled by the claim that this …”will take a few seconds”. It will take a few seconds to apply the configuration change but the repair will take hours (depending on the disks used)

screenshot of the final maintenance wizard screen
The rebuild will begin when “Apply” is clicked. It will take several hours, depending on the disks.

Finishing Up

You’ll see notification popups as the rebuild progresses.

Screenshots of notifications during drive swap
Notification sill appear during the drive swap

Now there’s not much to do except let the repair finish. Like I mentioned, I usually let this run overnight. The Synology DS 212J is still usable while the volume is rebuilding. Performance may be impacted if your activity is disk intensive. This particular rebuild of two 3 TB WD Red drives took just under 9 hours.


Here’s a gallery of the photos and screenshots from the article that can be viewed in order. Click the first one to open the slide show which you can click through in order.

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