Remove 2 drives from RAID 10 on RN104

[prix57]

Hello, I am sorry if this has already been posted.

I was wondering if there is a way to know which drives are which in a RAID 10 array setup on my RN104?  I want to take 2 drives out and put them into another NAS so I can then copy the data from the RN104 to the new NAS.

Thanks!

[StephenB]

It would be very convenient if the GUI showed that information.  Perhaps post that in the idea exchange.

[prix57]

I guess then my only option is the take out the 2 drives and hope it does not crash the current raid 10 array.

My guess would be bays 2 and 4 would be the safest bet.

[mdgm-ntgr]

Don't do that. Please send in your logs zip file (see the Sending Logs link in my sig).

[prix57]

Sorry for the delay.  I have followed the steps and emailed the logs

I will patiently wait for your reply.

Thanks.

[mdgm-ntgr]

Thanks for the logs.

I will need more information than what I can find in the logs.

I have sent you a PM.

[mdgm-ntgr]

Your NAS was running very old firmware from October 2013, so the logs didn't give the information I was after.

I have now updated it from 6.1.4 to 6.2.5 and then again to 6.5.0.

I would remove disks 0 and 2 (or 1 and 3 if counting 1-4) or disks 1 and 3 (or 2 and 4 if counting from 1-4)

You should remove the disks whilst the NAS is turned off.

For an explanation of how I came to this conclusion see below:

If you download the logs and look at mdstat.log you will see this:

    Number   Major   Minor   RaidDevice State

       0       8       51        0      active sync set-A   /dev/sdd3

       1       8       35        1      active sync set-B   /dev/sdc3

       2       8       19        2      active sync set-A   /dev/sdb3

       3       8        3        3      active sync set-B   /dev/sda3

The disks you remove should both be from Set A or both from Set B.

You can see in disk_info.log the order of the disks from left to right from channels 0 to 3 (i.e. 0, 1, 2, 3 - if it makes things simpler for you you could add 1 to each to get 1, 2, 3, 4).

So the disks are

Disk 0 (or 1): sdd

Disk 1 (or 2): sdc

Disk 2 (or 3): sdb
Disk 3 (or 4): sda

Doing a checksum of an early section of each of the disks I get this:
 

sda = 3d34fec6f4d73e548f01f2c73e30931e  -

sdb = 3d34fec6f4d73e548f01f2c73e30931e  -

sdc = f9c4a38e7b2ad3b82da93031de23906e  -

sdd = f9c4a38e7b2ad3b82da93031de23906e  -

If you were to remove both disks with matching checksums then that would take down your array.

So if you removed disks 0 and 1 (or 1 and 2 if counting from 1-4 rather than 0-3); or disks 2 and 3 (or 3 and 4 if counting from 1-4 rather than 0-3) that would take down your array.

[mdgm-ntgr]

One more thing when you get your new NAS, I would:

1. Put a scratch disk (must not be from your array) in the new NAS

2. Update the firmware to 6.5.0 (or later if you have updated your current NAS to newer firmware again by then)

3. Verify the update is successful

4. Power down both NAS

5. Remove the scratch disk

6. Move the 2 disks across (make sure you pick the right ones to move and place them in the same positions in the new NAS).

7. Power on.

I don't recommend using this method to move your disks across to a new NAS, but if you must try it this is how I would go about it.

It would be much better to simply get new disks for the new NAS and copy your data across from one NAS to the other using backup jobs.