Synology NAS - Lost a drive. How do I recover?

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#3499009 1-Jun-2026 08:06

Please offer some advice.

I had an old 6TB Drive (which I knew had errors and didn't really want to use it) and put it into Drive 1.

Drive 2 contains the good 6TB Drive.

The NAS rebuilt the Storage Pool.

In the meantime, I purchased an 8TB NAS Drive. I have not fitted it yet.

This morning:

1) Both drives critical. Then (and I didn't do anything) about 30 minutes later ...

2) Drive 1 Healthy, Drive 2 Critical. Then (and I didn't do anything...) about another 30 minutes later ...

3) Both drives Healthy.

So, I am thinking.

The original problem was:

Drive 1 - Critical

Drive 2 - Healthy

So, put the new 8TB Drive in Drive 1 and let it do its think and see what happens.

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Behodar

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#3499012 1-Jun-2026 08:24

It's been a while since I've had a failed drive but it might be the case that it reports both drives as critical while it's rebuilding, as the loss of either drive at that point will result in a catastrophic failure. Once the rebuild has completed, the pool is then healthy again.

alisam

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#3499013 1-Jun-2026 08:31

Behodar:

It's been a while since I've had a failed drive but it might be the case that it reports both drives as critical while it's rebuilding, as the loss of either drive at that point will result in a catastrophic failure. Once the rebuild has completed, the pool is then healthy again.

As far as I could ascertain, the pool had been rebuilt as there were no messages in Storage Manager.

Tinkerisk

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#3499014 1-Jun-2026 08:53

alisam:

Behodar:

It's been a while since I've had a failed drive but it might be the case that it reports both drives as critical while it's rebuilding, as the loss of either drive at that point will result in a catastrophic failure. Once the rebuild has completed, the pool is then healthy again.

As far as I could ascertain, the pool had been rebuilt as there were no messages in Storage Manager.

I don't have DSM, so I can't really comment on that. However, you might be able to access the S.M.A.R.T. parameters of each HDD and check how many errors are recorded there. Sometimes, an assessment is also provided there to help you interpret the significance of the diagnostic data—or to warn you of an impending drive failure.

In the best-case scenario, it was just a hiccup; in the worst case, you'll have to trade in another kidney—this time for the other drive. 😉

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fearandloathing

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#3499015 1-Jun-2026 09:07

For longevity of drives in Synology.
don’t hibernate drives, let them spin 24/7
enable monthly smart tests

Enable 3 monthly Full RAID scrubbing; this is the important one, as it reads and writes the entire drive surface regularly.

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#3499030 1-Jun-2026 10:37

fearandloathing:

For longevity of drives in Synology.
don’t hibernate drives, let them spin 24/7
enable monthly smart tests

Enable 3 monthly Full RAID scrubbing; this is the important one, as it reads and writes the entire drive surface regularly.

Thanks for this. I run DS220+ with 2 x 8TB WD red. I just checked storage manager and last time data scrubbing was completed was 2020 (I bought the DS in 2020).

So I should run a data scrub now and set up a 3-monthly schedule?

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#3499031 1-Jun-2026 10:39

dafman:

fearandloathing:

For longevity of drives in Synology.
don’t hibernate drives, let them spin 24/7
enable monthly smart tests

Enable 3 monthly Full RAID scrubbing; this is the important one, as it reads and writes the entire drive surface regularly.

Thanks for this. I run DS220+ with 2 x 8TB WD red. I just checked storage manager and last time data scrubbing was completed was 2020 (I bought the DS in 2020).

So I should run a data scrub now and set up a 3-monthly schedule?

yes

i would go 6 monthly as the absolute max for it. its checking all the data for any errors and recovering it if possible.

freitasm

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#3499038 1-Jun-2026 11:03

@alisam please, whatever you do, do not remove the original good drive for now. You replaced the failed drive with a drive that you knew had errors already. Not good.

Wait until it says the pool is healthy.

When it does, disable the drive you installed, the one you know had errors.

The pool will go unhealthy again. Swap with the new, good drive. Let the NAS do its work.

And make sure you have a backup of your important data.

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#3499451 2-Jun-2026 10:58

fearandloathing:

Enable 3 monthly Full RAID scrubbing; this is the important one, as it reads and writes the entire drive surface regularly.

Thanks for posting this: it prompted me to check my settings. I had scrubbing set for every six months, but it last ran in 2020! It turns out that although the schedule was set up, it had somehow become unlinked from the storage pool. I'd encourage everyone to review their settings and make sure that it's running.

freitasm

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#3499452 2-Jun-2026 11:02

Behodar:

fearandloathing:

Enable 3 monthly Full RAID scrubbing; this is the important one, as it reads and writes the entire drive surface regularly.

Thanks for posting this: it prompted me to check my settings. I had scrubbing set for every six months, but it last ran in 2020! It turns out that although the schedule was set up, it had somehow become unlinked from the storage pool. I'd encourage everyone to review their settings and make sure that it's running.

Scrubbing is quite an intensive operation, as it reads all data and, if it contains checksums, calculates them. I schedule it for every six months, and make sure it doesn't coincide with SMART checks either.

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alisam

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#3499552 2-Jun-2026 16:42

I believe I have just ruined a brand new 8GB WD Red NAS drive in 30 seconds.

I put the new disk in Drive 1. As I replace drives so infrequently, I found it hard to slide the drive evenly into the slot.

The DS216 Play has 2 drive slots, one on top of each other.

After inserting the disk, DSM did not recognise it (PS I had checked that the DS216PLAY would take a maximum disk of 8TB)

I took it out, but did find I had chipped part of casing near the terminals, because there was a small piece of loose plastic from the drive. The terminals did not look damaged.

I put it back, but still DSM would not recognise it.

I took it out and put it into a ORICO 2 bay dock, but Windows would not see it.

What a waste of good money and dreading telling the wife.

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#3499557 2-Jun-2026 17:01

I love Synology devices, but I'd have to say, the way they represent drive failures/raid degradation is pretty horrible. As an experienced IT person, I had a similar single drive failure recently and the UX of getting back to healthy and understanding the UI wasn't ideal in my opinion.

I am thankful I have a clear and technical understanding of this, and I could absolutely see someone misunderstanding the situation and making it worse. As someone mentioned, Synology do somewhat make up for this, with better than average tolerance for those issues.

I am a huge fan of HPE and their Smart Array Controllers (though recently I had a failure where the bays the drives were being reported in were in fact absolutely incorrect till a reboot, which nearly caused the wrong drive to be removed and 'replaced).

networkn

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#3499558 2-Jun-2026 17:02

alisam:

I believe I have just ruined a brand new 8GB WD Red NAS drive in 30 seconds.

I put the new disk in Drive 1. As I replace drives so infrequently, I found it hard to slide the drive evenly into the slot.

The DS216 Play has 2 drive slots, one on top of each other.

After inserting the disk, DSM did not recognise it (PS I had checked that the DS216PLAY would take a maximum disk of 8TB)

I took it out, but did find I had chipped part of casing near the terminals, because there was a small piece of loose plastic from the drive. The terminals did not look damaged.

I put it back, but still DSM would not recognise it.

I took it out and put it into a ORICO 2 bay dock, but Windows would not see it.

What a waste of good money and dreading telling the wife.

Don't panic yet, lets get a photo up in decent resolution of the business end of the drive and see what the damage is. If you haven't damaged the pins, you are likely absolutely fine. I am guessing you are slightly misaligned on the connector.

If you are in Auckland, and are willing to bring the NAS, and drive to me, I can take a look in person, gratis. Don't do anything else until you've either done that, or put up photos and waited to hear back from others here as to the next action.

alisam

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#3499568 2-Jun-2026 18:00

networkn:

alisam:

I believe I have just ruined a brand new 8GB WD Red NAS drive in 30 seconds.

I put the new disk in Drive 1. As I replace drives so infrequently, I found it hard to slide the drive evenly into the slot.

The DS216 Play has 2 drive slots, one on top of each other.

After inserting the disk, DSM did not recognise it (PS I had checked that the DS216PLAY would take a maximum disk of 8TB)

I took it out, but did find I had chipped part of casing near the terminals, because there was a small piece of loose plastic from the drive. The terminals did not look damaged.

I put it back, but still DSM would not recognise it.

I took it out and put it into a ORICO 2 bay dock, but Windows would not see it.

What a waste of good money and dreading telling the wife.

Don't panic yet, lets get a photo up in decent resolution of the business end of the drive and see what the damage is. If you haven't damaged the pins, you are likely absolutely fine. I am guessing you are slightly misaligned on the connector.

If you are in Auckland, and are willing to bring the NAS, and drive to me, I can take a look in person, gratis. Don't do anything else until you've either done that, or put up photos and waited to hear back from others here as to the next action.

Have a look at the photos first (thank you).

networkn

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#3499571 2-Jun-2026 18:17

Ok, I can't see damage to the pins, and the majority of the mechanism that guides your drive into the right place is intact, so in theory, lined up *correctly*, you'd be all set, though a fraction less securely.

I am thinking the reason your drive wasn't recognised by windows is the format of the drive or the partition structure, if one even existed. It's more likely entirely unformatted and has no partitions, so Windows doesn't 'know' about it yet.

Good news is you likely have a decent outcome still possible.

I have risotto on the stove, I'll pop back in a little while to provide more guidance, I wanted to give you some reassurance early. I'd hate for your wife to have fed you into a woodchipper feet first thinking all was lost :)

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