Can I combine different RAID levels in same NAS (WD PR4100)?

Is the following setup possible in a single NAS (WD PR4100):

2 x 8TB in RAID 1 (for video file streaming)
2 x 10TB in RAID 0 (for Time Machine backup)

Time Machine (20TB) would be used as backup of the NAS video files (8TB) and the computer’s (iMac) internal hard disk (3TB).

Is that a viable setup?

I would appreciate some advice on this since I was not able to find any specific information online. I am especially interested to understand if it is possible to efficiently combine different RAID levels and different disk sizes without degrading performance. Thanks.

Hi dr. mesmer,

The My Cloud device only supports a single RAID configuration and Time Machine creates a backup of only Mac to NAS or DAS.

Hi Brandon,
Thanks for clarifying. So unfortunately I’ll have to think of other ways of backing up my NAS and my Mac. I guess external hard disks for each is the only way?

Hi again,
I have just found somewhere that two same RAID configurations are possible in the PR4100. For example RAID 1 (2x8TB + 2x8TB). Can you confirm that please. Thanks.

“I found something somewhere” is hard to confirm without source…
It is possible to do when you configure mdadm manually but the WD firmware doesn’t support it via the GUI.

I just needed to know if it was possible. There was no need to refer to the source. So if I understand correctly, I can manually configure two RAIDS, but they have to be the same configurations.

Also, in that case can the two RAID 1 configurations be of different capacity?

Note that these modifications are done via SSH commands and it’s at your own risk (it’s not guaranteed to work, you may face data loss, it won’t integrate with the rest of the firmware so you may get warnings/errors, the web interface may not let manage it / create shares, changes may be lost on reboot, …).

All these warnings aside, you can play around with mdadm a bit. Here’s how to create a RAID1 array over 2 partitions. Note that this operation will destroy any data on those partitions.

mdadm --create /dev/md/name /dev/sda1 /dev/sdb1 --level=1 --raid-devices=2

The volume at /dev/md/name will get the size of the smallest partition (so yeah, different capacity is possible).

Once again, be careful with the command above. Only use it when you understand what you’re doing.

I understand the risk and will ask someone more knowledgeable to actually set it up. Thanks for clarifying this.