Volume data is degraded

[Warhead666]

Hi - I see this question has come up before, but I hope you can help with my specific problem. I have 2 x 3TB and 2 x 4TB Western Digital HDDs in my ReadyNAS 104.
My usage shows 1.96TB free out of a total of 9.08TB.
All four drives are blue in the admin screen and show as "Raid 1", and X-Raid is highlighted in green. 
Drive 4 is flashing and is sending me "Volume data is degraded". The log shows on Feb 26 (while I was on holiday, of course) Disk in Channel 4  changed status from Online to Failed. Following that, the logs continue to report Volume data is degraded.

I'm not really sure what to do next. I appreciate I'll need to buy a new HDD, but is it just a case of hot-swapping the failed drive for a new one. From Windows Explorer the files appear to be intact. Is it safe to assume that my data is OK?

Thanks in advance.

[StephenB]

---

@Warhead666 wrote:

Drive 4 is flashing and is sending me "Volume data is degraded". The log shows on Feb 26 (while I was on holiday, of course) Disk in Channel 4  changed status from Online to Failed. Following that, the logs continue to report Volume data is degraded.

 is it just a case of hot-swapping the failed drive for a new one. From Windows Explorer the files appear to be intact. Is it safe to assume that my data is OK?

It is normal for a volume with RAID redundancy to report that the volume is degraded when a disk fails.  That just means that there is no more RAID redundancy - so the data is at higher risk than normal.  The data should be ok, but if there is a second failure, you will lose it. 

Note that in many cases people purchase all their disks at the same time, and get identical models in the same shipment.  All the disks are in the same chassis, and have the same load.  While that doesn't mean that the disks will all fail at the same time, it's not that unusual for disks in a RAID array to fail close together.

Best practice is to make sure you have an up-to-date backup of your data (at least the data that can't be replaced).  FWIW, RAID redundancy isn't enough to protect it anyway - you really do need at least one backup on a different device.

---

@Warhead666 wrote:

I'm not really sure what to do next. I appreciate I'll need to buy a new HDD, but is it just a case of hot-swapping the failed drive for a new one.

That is the correct process.  The disk shouldn't be formatted - if it is, you'll need to select it and click on the format control on the volume page before it is added.

I usually test mine first - running the full generic test from vendor tools (seatools for seagate; dashboard for western digital).  I follow that up with a full erase/write zeros test - as I've sometimes had that test fail after the non-destructive tests pass.  Unfortunately dashboard no longer has that option - though if you have a copy of the older lifeguard diagnostic, it does have it.

If you generally use WD Red drives - I recommend against using the current WD Reds.  They all use SMR technology, and there are posts here from folks who've had issues with them in RAID arrays.  The problem is that the write speeds for SMR become glacially slow when the cache gets full.

So if you are thinking about these drives, I recommend using WD Red Plus instead (or Ironwolf).  Of course enterprise class is also fine (But IMO overkill for an RN104).  FWIW, I also don't recommend desktop drives (and if you get them, you should make sure they aren't SMR).   Both WD and Seagate have put SMR (or CMR) on their datasheets.

---

@Warhead666 wrote:

All four drives are blue in the admin screen and show as "Raid 1" 

---

That is a bit odd - normally you'd see RAID 5 with XRAID and 4 disks.  Can you double-check that?

Of course drive 4 should show up as failed in the graphic - unfortunately that seems to be a bit hit or miss.

[Warhead666]

Thank you for your quick and clear response (and the hopefully good news).

I've attached a screenshot - I note it does say "Raid 5" as well.

Does that look as it should? If so, I'll get straight to ordering that new drive.

[Sandshark]

Yep, that's the normal display for a single failed drive but data still intact due to RAID.

[Warhead666]

OK, I bought a new 14Tb drive and hot-swapped it for the failed Disk 4, thank you @StephenB 

While waiting for it to arrive, Disk 3 had been complaining of ATA failures, and on installing Disk 4, Disk 2 appears to have died completely. I've since removed it.

I've now got the following - can anyone advise what to do next?

How do I "remove inactive volumes"?

[StephenB]

---

@Warhead666 wrote:

OK, I bought a new 14Tb drive and hot-swapped it for the failed Disk 4, thank you @StephenB 

While waiting for it to arrive, Disk 3 had been complaining of ATA failures, and on installing Disk 4, Disk 2 appears to have died completely. I've since removed it.

---

Did disk 2 fail before disk 4 resynced?  I'm guessing that is the case.

RAID-5 can't handle 2 failed drives.  It might be possible to recover if the failed disk 2 and/or disk 4 can be cloned.  But this would be tricky, and not something easily dealt with on the forum.  Netgear offers a data recovery service ( https://kb.netgear.com/69/ReadyNAS-Data-Recovery-Diagnostics-Scope-of-Service) - there are others who specialize in this as well.  

[Warhead666]

Yes, I have a feeling Disk 2 died overnight as Disk 4 was getting bedded in.

I'll see what Netgear support have to say about it.

Thanks for your quick reply.