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Double Disk Degrade
Hi, I have had a potentially catastrophic issue with my RN214. I have been running 2x 6TB in Trays 1 and 2 under RAID1. I had originally puchased two 6 TB WD Red drives back in 2017 which worked until last year when one degraded (in Tray2). I couldn't get my hands on WD RED 6TB drive so went with a Seagate Ironwolf 6TB which did the trick.
In November 2021, I received a message on the LCD that the Ironwolf in Tray 2 had degraded, which was odd, as it was relatively new. As it was under warranty, I took the disk out, powered down the system and sent it off to Seagate for a replacement. I recevied my replacement last week and powererd up the Readynas to perform a hot swao and rebuild from the WD Red in Tray 1. During the reboot, I got the message that the Tray 1 WD Red disk had degraded (which was strange because the system had been powered down). I got a shock and realised my data was at risk and immediately powered down the system, and am now afraid to reboot it !.
So I now have a Raid1 with an original WD Red drive in tray degraded and the second disk new in Tray 2.
Is there any way I can recover the data on disk 1 ? Should I restart the system and let it re-sync only to tell me it is degraded ? I am concerned that if I allow it to re-sync, it will somehow lose the data on Tray 1 while trying to re-sync it with the new drive in tray 2?
Thanks very much in advance.
colmcc wrote:
During the reboot, I got the message that the Tray 1 WD Red disk had degraded (which was strange because the system had been powered down).
One clarification - RAID volumes are degraded, not individual disks. You started with a RAID-1 volume, and removed a disk. That will give you a degraded status, until the volume is resynced with a disk replacement. "Degraded' means you no longer have RAID protection.
So far this is normal status - but we are assuming that you removed the correct disk in November.
colmcc wrote:
I got a shock and realised my data was at risk and immediately powered down the system, and am now afraid to reboot it !.
Even though the status is normal, you are correct in thinking your data is at risk. One thing it's important to understand is that your data is always at risk unless you have a backup plan in place. RAID protection isn't enough to keep your data safe.
The main risk you are facing now is the possibility that disk 1 (the WD disk) will fail during the resync. If that were to happen, you would lose all your data.
You can address this by backing up your data (perhaps to a USB drive) before proceeding with the resync. To do this, you'd remove the new disk (while powered down), and then boot up the system read-only. Instructions on are on pages 58-59 of the hardware manual: https://www.downloads.netgear.com/files/GDC/READYNAS-100/ReadyNAS_%20OS6_Desktop_HM_EN.pdf Then back up the data to the USB drive.
The other option is to power up, and let the resync proceed - living with the risk. Normally resyncs will complete successfully - so the odds are quite good you'll get away with it, unless you have other indications in the log zip file that suggest disk 1 isn't completely healthy. (Note you can use the reboot procedure I outlined above, and then download the log zip file instead of backing up the data).
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colmcc wrote:
During the reboot, I got the message that the Tray 1 WD Red disk had degraded (which was strange because the system had been powered down).
One clarification - RAID volumes are degraded, not individual disks. You started with a RAID-1 volume, and removed a disk. That will give you a degraded status, until the volume is resynced with a disk replacement. "Degraded' means you no longer have RAID protection.
So far this is normal status - but we are assuming that you removed the correct disk in November.
colmcc wrote:
I got a shock and realised my data was at risk and immediately powered down the system, and am now afraid to reboot it !.
Even though the status is normal, you are correct in thinking your data is at risk. One thing it's important to understand is that your data is always at risk unless you have a backup plan in place. RAID protection isn't enough to keep your data safe.
The main risk you are facing now is the possibility that disk 1 (the WD disk) will fail during the resync. If that were to happen, you would lose all your data.
You can address this by backing up your data (perhaps to a USB drive) before proceeding with the resync. To do this, you'd remove the new disk (while powered down), and then boot up the system read-only. Instructions on are on pages 58-59 of the hardware manual: https://www.downloads.netgear.com/files/GDC/READYNAS-100/ReadyNAS_%20OS6_Desktop_HM_EN.pdf Then back up the data to the USB drive.
The other option is to power up, and let the resync proceed - living with the risk. Normally resyncs will complete successfully - so the odds are quite good you'll get away with it, unless you have other indications in the log zip file that suggest disk 1 isn't completely healthy. (Note you can use the reboot procedure I outlined above, and then download the log zip file instead of backing up the data).
Thanks a lot for the quick response. And now I finally get the concept that RAID = Degrade and I should have some contingent back-up in place.
OK, so I will try the manual back-up to USB drive before I re-sync, and see what happens.
Fingers crossed :).
Thanks again !
Just a quick follow-up on your advice, so I did the manual back-up to a USB drive and was able to retrieve the data, and then perfromed a re-sync with the new drive and it was successful, so back to healthy statius, just in time for Christmas !
Now I need to think about a robust contingency for RAID.....
Thanks again.
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