Forum Discussion

mwagonermpm

Follower

May 04, 2016

XRAID turned RAID5 into RAID6 when adding a drive

When I added a drive, my RAID5 config changed to RAID6. Is it supposed to do that?

Adding Disks

Danthem

NETGEAR Employee Retired

May 04, 2016

When you go past 6 disks xraid will turn your RAID5 to a RAID6

"X-RAID® dynamically changes raid RAID1 for 1 - 2 drives. RAID5 for 3 - 6 drives. RAID6 for 7+ drives"

You can try out different setups here:

http://rdconfigurator.netgear.com/raid/index.html

StephenB

Guru - Experienced User

May 04, 2016

Danthem wrote:

"X-RAID® dynamically changes raid RAID1 for 1 - 2 drives. RAID5 for 3 - 6 drives. RAID6 for 7+ drives"

I agree with the logic (though I wonder what would happen if that conversion required shrinking the volume size - which could be required if the drives aren't the same size).

But I think there should be a confirmation on the UI before the conversion happens.

mdgm-ntgr
NETGEAR Employee Retired
May 05, 2016
It's not sensible to use RAID-5 with that many disks.

The volume wouldn't be shrunk. Attempting to shrink a volume is dangerous.
- StephenB
  Guru - Experienced User
  May 05, 2016
  mdgm wrote:
  
  It's not sensible to use RAID-5 with that many disks.
  
  I agree. But I still think a UI confirmation is a good idea. Once it converts, there's no going back. And a user who really needs the capacity might prefer to switch to flexraid, and set up a jbod volume instead.
  
  mdgm wrote:
  
  Attempting to shrink a volume is dangerous.
  
  Understood. So what does happen if I have 2x6TB+4x4TB, and then I add a 6 TB drive to the array?
  - Retired_Member
    May 05, 2016
    StephenB wrote:
    Understood. So what does happen if I have 2x6TB+4x4TB, and then I add a 6 TB drive to the array?
    
    You start with 2x6TB + 4x4TB in RAID5, so you have one RAID5 of 6 partitions of 4TB (equivalent to 5 capacity + 1 parity), and one RAID5 of 2 partitions of 2TB (equivalent to RAID1, 1 capacity + 1 parity).
    When adding a 7th HDD of 6TB, you reshape the first RAID5 of 6 partitions of 4TB to a RAID6 of 7 partitions of 4TB (equivalent to 5 capacity + 2 parity, so same capacity), and reshape the second RAID5 of 2 partitions of 2TB to a RAID6 of 3 partitions of 2TB (equivalent to 1 capacity + 2 parity, so same capacity).
    
    https://i.imgur.com/jn2KmAG.png