Data recovery question - old RAID drive

[Derek M]

Hi,

I've been doing a lot of moving of data about and installing new network drives.

In the process, I have now found that some data I thought I had moved across to a new network drive had not been moved across...  Oh dear...

However, I know the data in question is still intact on one of the 2TB RAID1 drives removed from my Alt-F DNS-320L when I upgraded them to 6TB drives at the start of the process.

The DNS-320L is now fully equipped with its 2 new 6TB drives and the RAID1 is working as expected (but with an element of the data missing).

Is there a way for me to browse to and extract the missing data from the old 2TB drive, so that I can reinstate it on the new, upgraded 6TB RAID1?

Very grateful for any help that may be available!

[Tom Schmidt]

I suggest that you shutdown your DNS-320L NAS, label your 2 6TB drives left and right, then remove them.  Install the old 2TB drive and power up the NAS.  You should then be able to recover the files you need from the degraded RAID on the old 2TB drive.  You could mount a USB thumb drive on the NAS, or copy the files to a system on your network.  When done, shutdown again, remove the 2TB drive, insert the 2 6TB drives in the same slots as before, and power back up.

Tom

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[John Travell]

If you are running Windows on your PC, do what Tom said. 

With Alt-F the on-disk file system is almost certainly ext-4, even in a raid1 device, and fully supported by almost any version of Linux. So if you have escaped the Borg, you could put the drive in your desktop and mount it, or boot off a live USB, and use that to copy the data. Personally I would recommend Linux Mint for that, as the user interface is very similar to Windows 7 on steroids. Some people see that UI as dated, I see it as comfortable and familiar, I don't need flash for the sake of flash.

To view this discussion visit https://groups.google.com/d/msgid/alt-f/CAP7YgkzBUUQJ07zEDtYcrR8Z9Yn7fgoyqOjVyZyvyEZhmKgW_g%40mail.gmail.com.

[Derek M]

Thanks Tom.  

Follow-up questions for that suggestion:

• Just a normal power button shutdown, nothing else?
• The old 2TB drive doesn't have a L or R label (schoolboy error - too keen to get moving with the bigger drives) - if I put it in the wrong side, will it a) damage it, b) not damage it, but just won't work or c) it won't care because it will be the only drive
• should the degraded RAID just work straight off - no reconfiguration required?

Derek

[Tom Schmidt]

• A shutdown from the web user interface would be the cleanest.
• It should not matter which slot you put the old 2TB disk in, it should recognize it.
• The degraded RAID may want to run a file system check, so you may need to let that complete.  It could take hours to run.  You should not need to reconfigure anything unless you changed the shared volume names.

Tom

To view this discussion visit https://groups.google.com/d/msgid/alt-f/b774fef6-5efe-43f5-a757-175f787d6ef3n%40googlegroups.com.

[John Travell]

You said it was Raid1, that means each drive in a set hold an exact copy of the data on the other drive, so your single drive will just be seen as a degraded set with complete data. 

As to which side it goes, my '327 has never complained. When I upgraded my 2tb to an 8, I took out both drives, put the 2 into the 'other' slot and the 8 where the 2 used to live, then formatted the 8 and copied 2>8. No problems at all. 

For you, if you plan for the new drive to be part of a Raid1, take out the 2, put in the second new drive and create your set, being VERY careful which drive is the source.

JohnT.

To view this discussion visit https://groups.google.com/d/msgid/alt-f/CAP7YgkzX4wBKBHsAdTrQokV3hw7BRrokMcVzkZQFF3nONd5YHA%40mail.gmail.com.

[Derek M]

I'm afraid it didn't work.

I went through a lot of trials a tribulations when moving over to the 6TB drives, firstly trying to copy over from the old to btrfs on the new, hoping to ultimately end up with a btrfs RAID system, but came across the bug that dumps one of the drives out of the array...

After some consideration I abandoned the btrfs idea and went for a "fresh start" ext4 raid 1 array with the new 6TB drives (because I had convinced myself I had taken all the data off the drive and could simply copy it back on there).  Old settings got deleted, etc.

All was fine until I found a couple of chunks of data that had been missed...
I may therefore need to mount it to a linux system - I do have one upstairs that I use for streaming

Thanks for trying! 

[Derek M]

Looking at the 2TB now, connected to a linux raspberry pi that I have running elsewhere, I can see the partitions:

They would have been created under the original D-Link OS, rather than Alt-F.  sda2 should contain the data required

[Joao Cardoso]

A domingo, 1/03/2026, 15:50, Derek M <munro...@gmail.com> escreveu:

Looking at the 2TB now, connected to a linux raspberry pi that I have running elsewhere, I can see the partitions:

They would have been created under the original D-Link OS, rather than Alt-F.

No, if D-Link partitioned they would have a 500MB sda4 partition.

  sda2 should contain the data required

Yes

Why don't you just put the 2TB disk on a SATA to USB enclosure and attach it to the box running Alt-F?

Alt-F should recognize and assemble a degradated RAID1 and mount the filesystem on it.

To view this discussion visit https://groups.google.com/d/msgid/alt-f/9627a6d8-0898-43d3-a5e9-faf4904c7ec1n%40googlegroups.com.

[Derek M]

Hi  João,

Thanks.  I have done this and it sees the drive as sdc, but doesn't automatically recognize it and assemble a degraded RAID 1 / mount the filesystem. Do I need to do this manually through the RAID area?

[Joao Cardoso]

On 01/03/26 23:09, Derek M wrote:

Hi  João,

Thanks.  I have done this and it sees the drive as sdc, but doesn't automatically recognize it and assemble a degraded RAID 1 / mount the filesystem. Do I need to do this manually through the RAID area?

That's odd, because the algorithm to assemble the RAID and mount the filesystem is the same for box SATA-plugged or USB-plugged disks. Unless you have changed something during your attempts...

Can you please put again the disk in the SATA to USB enclosure, plug it to the box, execute the following commands and post the results?

Assuming that the disk is recognized as sdc and the partition sdc2 exists (sda and sdb will be your 7TB disks)

fdisk -l /dev/sdc

blkid /dev/sdc2

mdadm --examine /dev/sdc2

cat /proc/mdstat

Thanks,

João

To view this discussion visit https://groups.google.com/d/msgid/alt-f/2df5758a-2715-4730-b0b2-72cb663301dbn%40googlegroups.com.

[Derek M]

So, I powered the box down, attached my USB caddy to it with the 2TB drive in and restarted.

That seems to really confuse the 320L.  Screenshots attached:

It hasn't mounted anything yet and I wonder, is it just analyzing the disks?  

I'm just a bit worried that it hasn't mounted sda / sdb as the normal standard md0 RAID1 array

[Joao Cardoso]

On Monday, March 2, 2026 at 2:19:37 PM UTC munro...@gmail.com wrote:

So, I powered the box down, attached my USB caddy to it with the 2TB drive in and restarted.

 

You don't need to power-down the box, it's USB, you just plugged it in (but don't just unplug if there are mounted file systems) 

That seems to really confuse the 320L.

yes

 

  Screenshots attached:

That is not what I have asked for. You should ssh or telnet the box as the "root" user and after login type the commands I asked for and copy and post its outputs.
You can install an openssh client in windows, it's a windows optional feature, just ask Google how to install openssh on windows 11. Then, open a cmd window and type ssh root@<your_nas_name_or_ip> and type the commands I asked for. (but you have a raspberry, aren't you keen on the command line? :-)

It hasn't mounted anything yet and I wonder, is it just analyzing the disks? 

I don't think so, Load is low, but the Status screenshot is cropped, I can't see it all

 

I'm just a bit worried that it hasn't mounted sda / sdb as the normal standard md0 RAID1 array

Obviously the RAID web page is "confused", but both from it and from the Status page, no RAID has been assembled, "md0" it's stopped/Inactive.

The fact that the webUI is "confused" makes me believe that the 2TB disk has suffered some modification.

 

Power down the box using the webUI or power button, restart only with the 6TB disks, see if everything is OK, ssh the box as instructed, plugin the USB disk enclosure and execute the commands I asked for. They are only informative, no action is taken.

I'm looking for details about the 2TB disk in order to provide you with a command that will assemble the RAID.