Synology NAS After Power Outages: What To Know

Some people barely notice power outages – especially brief brownouts. But if you own a NAS, you should be very wary of them – because even a small power outage could result in big problems, including potentially losing your data.

Here’s exactly what you need to know about power outages as a Synology owner, and also why a UPS is often a crucial purchase.

Key Points

  • A NAS is particularly susceptible to data loss (or worse) after a power outage.
  • Using a UPS can greatly reduce the risk of any issues.
  • However if you didn’t have a UPS, you should reboot your NAS and run a few health checks.
  • Running the BTRFS file system and adding a start-up job each morning can also help.

Why Synology NASes Can Struggle After An Outage

A crossed out NAS with the question Will your NAS still work after an outage

A Synology NAS might sound like a simple device (“it stores a few files, so what?”), but it’s actually a full-blown computer with a motherboard, CPU, RAM, storage array – and of course, your storage drives. It has the potential to run dozens of packages, including VMs and CCTV surveillance stations – and more.

They can also store millions of files, all of which should be accessible without any delay (that’s the original aim of a NAS, after all). As a result, a NAS can actually be quite a complicated system – and if its power is interrupted due to a power outage, real damage can occur. Before discussing what to check (and/or fix) after a blackout, I wanted to quickly discuss why a UPS is a critical device to purchase for your NAS.


My new APC UPS next to my Synology NAS
My new APC UPS next to my Synology NAS

A UPS stands for Uninterruptible Power Supply, which is a separate device that contains rechargeable batteries (like your phone or laptop). You plug the UPS into a wall plug, and then your NAS connects to this.

If there is a brownout or blackout, your NAS won’t suddenly turn off: it will instead start drawing power from the UPS’ battery backup. Neat!

It’s worth noting that many consumer-grade UPSes ‘only’ cost a few hundred dollars, and therefore they are designed to last for minutes – not hours. In other words, you can’t expect them to run your NAS for an entire day while your neighborhood recovers from a severe blackout.

Instead, they are designed to detect a blackout – and then gracefully shut down your NAS, so that it won’t have any issues with corruption or lost files:

Enabling UPS support within the Synology NAS admin console
Enabling UPS support within the Synology NAS admin console

You can then configure your NAS to automatically start up when the power is back on (i.e. once your UPS has switched from battery backup to full power, after the power outage is resolved).

What To Check (And Fix!) On Your NAS After A Power Outage

My Synology DS220 NAS with two internal drives connected to a network switch
My Synology DS220+ NAS.

While UPSes are awesome, if you didn’t have one when there was a power outage, here’s what you should immediately check – and potentially fix.

Struggling To Access DSM (The Admin Panel)?

If you are struggling to access the Synology admin panel (called the DSM), you might just be experiencing some temporary glitch. You should firstly try turning your Synology device off and back on again, via the power button on the front. This can resolve a range of weird post-power outage glitches, especially if you are trying to use QuickConnect.

However if you still can’t access DSM, getting a “page not found” type error even via local access, you should open up in your browser (just be sure that your device is connected to the same network as your Synology NAS).

This useful tool will scan your local network for signs of your Synology NAS, hopefully responding with something like this:

The web service that shows my NAS local IP address
The web service that shows my NAS local IP address

This will show you the IP address of your NAS. It is possible that this has changed due to the power outage, meaning that any old bookmarks you hold for your NAS are now incorrect (hence why you were seeing the “this site could not be reached” type errors earlier). Once you have the new address, you can use this to access the admin panel as normal.

Tech Tip: because the IP address can change, Synology instead recommends that you navigate to synologynas:5000 (or synologynas.local:5000 on a Mac or Chromebook). This is a shortcut hostname that will always try and resolve to your NAS, no matter the IP address.

If you still don’t have any luck, you should check the lights on the front of your NAS in-case there are any warning lights showing. There can be dozens of different meanings (depending on which light is showing up), but Synology’s help page is quite useful for debugging this.

Finally, computer restarts – especially after power outages – can result in some weird issues. In rare cases, the internal battery can actually fail, causing a range of time-based problems. Some users found that they needed to update the time on their NAS before they could properly use it.

Could Your Synology Settings (Or Packages) Be Damaged?

The HDD Hibernation features in the Synology NAS control panel
The Synology NAS control panel

It’s not just start-up issues that you have to worry about after a power outage. Some of your Synology’s settings could become corrupted after a blackout, especially if you were actively changing settings within the Control Panel at the time of the outage.

If you notice any unexpected behavior from your NAS after an outage, you should specifically double check any related settings within the control panel.

Secondly, some packages can be quite brittle – especially services like Plex and virtual machines (Docker). These heavyweight packages can often corrupt after an unexpected shutdown, potentially resulting in a failed package state that requires a full uninstall and reinstall of the package.

The Uninstall option for the Docker application in Synology Package Manager
The Uninstall option for the Docker application in Synology Package Manager

This can be the most frustrating part of a brownout or blackout, because a quick outage might require you to spend hours rebuilding your packages back to their original state.

Your Drives Might Be Damaged

One of the worst things that can happen to your NAS after a power outage is your storage drives start failing. An unexpected shutdown can be tough on a drive (especially older hard drives, since they have physical, moving parts).

You might not notice any immediate problem, but your drives might develop a bad sector – essentially meaning that some of your files are at risk (without you knowing it). As a result, you should immediately run health checks on your drives after a blackout.

To do this, launch the Storage Manager within DSM, then click “HDD/SDD”. You should now select each drive, click “Health Info” and finally “S.M.A.R.T”, where you can quick off either a long or quick test:

Triggering a manual SMART disk health check on one of my Synology drives
Triggering a manual SMART disk health check on one of my Synology drives

Unless you actively suspect that your drive is damaged, a quick test will probably be fine after a power outage. However if the test results are inconclusive, or you get other issues with your Synology NAS, you will want to schedule an extended test just to be sure.

All this assumes that your NAS is freely turning on after a blackout, of course. If you struggle to even boot or access your NAS, or you see error lights for your drives, you should purchase a new drive – and insert only this one into your Synology device. You should then try starting up your NAS and accessing the Synology set-up assistant as though it’s a clean install.

This step might seem drastic, but it might allow you to recover from a no-boot-up situation after a blackout. Once you are back up and running, you would then need to copy the files from your old drives via the USB port (which will also require the purchase of an external USB enclosure).

A 1TB Western Digital SATA hard drive
My old 1TB WD Blue drive will need an external USB enclosure to restore its files.

Tech Tip: the reason you will need an external USB enclosure is because you can’t just insert your old drivers into the drive bays of your NAS. Doing this will reformat them (when you come to add them back into your NAS’ storage pool). You can only retrieve your files by using the USB port to copy the files.

Is Your Synology Set To Auto Power-On After An Outage?

Synology offers a really useful feature, where your NAS can automatically power itself back on after a power outage. If you live in an area with lots of blackouts or brownouts, you should double check that this setting is enabled – otherwise you will constantly find your NAS unresponsive.

To do this, go into your admin panel, launch the control panel and go to “Hardware & Power”. There will be an option called “Restart automatically when power supply issue is fixed” – make sure this is enabled (mine was disabled by default):

Synology offers a useful feature to automatically start up when power issues are resolved
Synology offers a useful feature to automatically start up when power issues are resolved

This will help to ensure that your NAS is always powered on, even if you live in an outage-heavy area.

Tip: Add A Start-up Scheduled Job Each Morning

If you find that the above option doesn’t work reliably for you, you can also add a scheduled job that always starts your NAS each morning (or even, multiple times a day). If your NAS is already running, the job simply won’t do anything – which is neat.

To do this, again go into Control Panel and then “Hardware & Power”. Click the “Power Schedule” tab and then “Create”:

How to create a new power schedule within the Synology NAS DSM
How to create a new power schedule within the Synology NAS DSM

Ensure that “Startup” (not Shutdown!) is ticked, then enter a time – then hit OK to save the schedule:

Adding a new power schedule to my Synology NAS within the control panel
Adding a new power schedule to my Synology NAS within the control panel

The beauty of this approach is that it will only do anything when your NAS is actually shut down, helping you to naturally recover from power outages.

Why BTRFS File Systems Are The Best

When you first set up your NAS, you might not have worried about the file system type too much – but this actually contained a crucial choice. The BTRFS file system is a modern file system that is specifically designed to protect your files, adding fault tolerance and data protection mechanisms (compared to file systems like ext4 and NTFS).

Having all your Synology files running under the BTRFS file system will help to prevent file corruption (or data loss) when an unexpected blackout occurs. You can confirm your current file system by launching Storage Manager, clicking your storage pool (on the left sidebar) and clicking the down arrow next to your volume (towards the bottom):

Verifying the current file system for my main volume on my Synology NAS
Verifying the current file system for my main volume on my Synology NAS

Unfortunately if you are running on ext4, you can’t simply ‘click a button’ to convert to BTRFS instead. You instead need to backup your data and files elsewhere, remove the ext4 volume, create a BTRFS volume – and move all your files back. This process is explained in full in the following YouTube video:

Is Your NAS Failing To Boot Up At All?

In the worst case, your Synology NAS might fail to boot up at all after a blackout. There are a few things you should do in this case:

  • Check if there are any lights on at the front of your NAS. If there are error/amber lights on, then you should refer to the NAS’ manual to try and work through the issue and hopefully resolve it.
  • If no lights are on at all, double check that the power adapter is fully inserted (into your NAS, and the wall outlet) – and then try pressing the on/power button again. It might simply be the case that the power adapter has been knocked out by accident.
  • If all else fails, try buying a new drive (or loaning one off someone) and inserting just this into your NAS. Then try and run through the new NAS set-up process. It’s possible that the start-up files in your old drives have become corrupted, so this approach can sometimes help to get your NAS started up again.

If nothing else works: Synology’s customer support team are fairly helpful – although you might find that you aren’t covered under the warranty if the cause was a power outage (and you weren’t running a UPS).

Final Tech Tip: Have Backups!

Before wrapping up, I wanted to quickly cover another PSA: always have backups!

Synology make it really easy to create backups via HyperBackup and Synology C2 (i.e. their own backup solution), however you can buy backup space from any other source and use Synology’s other backup solutions – which includes FTP and rsync functionality.

Whether you run a NAS for personal convenience or as part of a business, having off-site backups is crucial because a simple power outage can potentially destroy all your files. However with backups, you can then simply buy new drives, re-create the volume (as BRTFS, of course!) and then restore all your files.

cropped A picture of me Tristan
About Tristan Perry

Tristan has been interested in computer hardware and software since he was 10 years old. He has built loads of computers over the years, along with installing, modifying and writing software (he's a backend software developer 'by trade').

Tristan also has an academic background in technology (in Math and Computer Science), so he enjoys drilling into the deeper aspects of technology.

Tristan is also an avid PC gamer, with FFX and Rocket League being his favorite games.

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