I had 2 disks in it as Raid 1. I tried to read search the community for what would happen if I added another pair of disks. Frankly, I found it entirely confusing (should there not be a manual for what happens when you add disks?). I though it would just make another raid 1 volume but I guess not becuase, on its front panel, it said something about RAID 5 and now it's "reshaping the data". So, what in god's name have I done? What will I end up with?

When you go to the third disk, it converts the volume to RAID-5. That gives you protection from a single disk failure. Total capacity is the sum of the disks minus the largest. For instance, if you started with 2x4TB and now have 4x4TB, the volume grows from 4 TB to 12 TB. The NAS reports the 12 TB in TiB (1 TiB = 1024*1024*1024*1024 bytes), so it will show 10.9.

RN104 added 2 disks to raid 1 system. Don't know what it's doing

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StephenB
Guru - Experienced User
Nov 20, 2016
When you go to the third disk, it converts the volume to RAID-5.

That gives you protection from a single disk failure. Total capacity is the sum of the disks minus the largest.

For instance, if you started with 2x4TB and now have 4x4TB, the volume grows from 4 TB to 12 TB. The NAS reports the 12 TB in TiB (1 TiB = 1024*1024*1024*1024 bytes), so it will show 10.9.
- adiamond2
  Aspirant
  Nov 20, 2016
  So, if I undertand you correctly, given I had 2x 2TB disks (in a raid 1), and I added 2x 4TB disks the new thing will look like one big 2+2+4=8GB volume?
  
  So, is there a document that I missed that explains what the result will be if you add or replace disks given a particular starting configuration?
  
  Thanks
  - StephenB
    Guru - Experienced User
    Nov 20, 2016
    adiamond2 wrote:
    
    So, if I undertand you correctly, given I had 2x 2TB disks (in a raid 1), and I added 2x 4TB disks the new thing will look like one big 2+2+4=8GB volume?
    
    Well 8 TB, but otherwise correct.
    
    When you replace disks, you can either replace them with one that's the same size, or replace them with one that's at least as large as the biggest disk already installed.
    
    Similarly, when you fill an empty slot, you need to add a disk that's at least as large as the biggest disk installed.
    
    There is an XRAID calculator here: http://rdconfigurator.netgear.com/raid/index.html However, it doesn't clearly state the two constraints above. FWIW, there are other constraints with OS 4.2 and OS 5 ReadyNAS.