If you’re in this current situation, hopefully you’re running a RAID setup so that you didn’t lose any data. If so, that’s one less thing to worry about. Plus, RAID lets you keep your NAS up and running like normal even if one of the hard drives dies, so there’s no rush to replace the drive right away. That said, you do lose some (or all) of your fault tolerance until you can replace the failed hard drive. Replacing it sooner rather than later is ideal.
Step One: Identify the Failed Drive
When a hard drive fails, Synology lets you know about it by loudly beeping at you. On top of that, you’ll get warnings about a “degraded” volume.
You can see which hard drive ended up failing by logging into DiskStation Manager and clicking the main menu button in the top-left corner.
Next, open up the “Storage Manager” app.
Then, in the left-hand sidebar, click “HDD/SDD” to show a list of the hard drives and their status.
Next to each drive, you’ll see a green or red status, depending on the state of the drive. When everything is functioning properly, you’ll see “Normal” shown in green next to each drive. But a failed hard drive will display a red “Crashed” or “Failed” status. In my case, the failing hard drive was showing up as “Normal”, but it was buzzing loudly, which is a good sign of a faulty drive in the making.
The disk number will be the drive’s position in the NAS enclosure from left to right. So if “Disk 2” failed, then it’s the second hard drive from the left.
Step Two: Remove and Replace
After determining which hard drive went kaput, you can remove it from the NAS enclosure. You may have to completely shut down your NAS first before removing a hard drive, but most Synology NAS boxes support hot-swapping. In that case, you can leave it powered on and remove and insert hard drives all day long without an issue.
It’s usually a good idea to have a spare drive ready to go. If you do, just slide the new one in after removing the failed drive.
If you don’t have a spare drive, don’t worry. You can still remove the failed drive, and then worry about getting a new drive (RMA a drive that’s still under warranty or buy a new drive if not). For what it’s worth, though, it’s usually good practice to have a hot spare ready to go whenever something like this happens, but it’s not absolutely necessary.
RELATED: How to RMA a Defective Product
Of course, until you replace the drive, your NAS will continue to give you warnings, so be prepared to put up with that.
Step Three: Test the New Hard Drive
After you’ve installed the new hard drive to replace the old, failed one, it’s important to make sure it’s working properly before you putting it into action (because there’s always the chance of receiving a DOA drive in the mail). The best way to do this is to run a SMART test.
Most modern hard drives are self-monitored and they will let you know if they’re failing or going to fail soon. You find out this info by running a SMART test on the drive. To perform a SMART test on your new drive in your NAS box, go into Storage Manager and navigate to the HDD/SDD screen again. Select the new drive, and then click the “Health Info” button.
Click the “S.M.A.R.T. Test” tab at the top of the window.
From there, you can select either the “Quick Test” or “Extended Test” option. We recommend the extended test, because even though it takes longer, the results are much more accurate. Hit “Start” when you’re ready.
You’ll receive a pop-up confirmation that shows you the approximate amount of time the test will take. It will take a while (at least several hours), so be patient.
While running, you’ll see the status and progress of the SMART test amongst the other details of the new drive. You can continue to use your NAS like normal, but you may notice decreased performance during the test.
Step Four: Repair the Volume
After you have the new hard drive installed and fully tested, it’s time to repair the volume and rebuild the RAID. In Storage Manager, click the “Volume” option in the left-hand sidebar.
Click the “Manage” button at the top of the window.
In the new window that comes up, select the “Repair” option, and then hit the “Next” button.
Select the new hard drive, and then click the “Next” button again.
You’re warned that all data on the new drive will be erased. Hit the “OK” button to confirm.
On the next screen, click “Apply” to begin the repair process.
Depending on the size of the RAID, this process could take several days, so be patient. You can see its progress from the main “Volume” screen in Storage Manager.
As with running the SMART test, you can continue to use your NAS as usual, but you may notice decreased performance during the repair process. Also keep in mind that you aren’t able to change the RAID type as part of the repair (e.g. switching from RAID 1 to RAID 5 if you installed more drives). You have to repair the original array first, and then you can change the RAID type later.