Changing Drives in the My Cloud EX2

I have just ordered a My Cloud EX2 diskless unit. I already have two WD hard drives (one 3TB + one 2TB). My plan is to use these drives in a RAID 1 configuration. I believe this will limit me to a total capacity of 2TB since that is the size of the smaller disk.

I’m wondering if I may replace the 2TB drive with a 3TB drive at a later date without losing the data on the existing 3TB drive. The steps I plan to follow are:

  1. Currently install the 3TB and 2TB drives using RAID 1 (resulting in 2TB of storage) until I can buy another drive.

  2. Later, purchase another 3TB drive to replace the 2TB drive.

  3. When I have the new drive, ensure Auto Rebuild is enabled, shut down the EX2, replace the 2TB drive with the new 3TB drive.

  4. Power on the EX2. I assume the Auto Rebuild feature will then mirror the data on the first 3TB drive to the new 3TB drive. This should leave me with 3TB of storage in a RAID 1 configuration.

Is the above scenario reasonable, or should I just move the data to another location and start out fresh when I have both 3TB drives?


I have a diskless EX2 too but only with one drive in JBOD. I don’t know the RAID behavior of the EX2 but my strong hunch is you will lose your data if you try to do auto-rebuild of RAID and try to upgrade to the full capacity after having both 3TB drives in. This I don’t know for certainthough - if someone else can confirm definitively one way or another, then great.

Also, I am not sure what kind of drives you are using but sometimes people repurpose their green or other drives they have lying around rather than spend on Red (NAS) drives. I strongly recommend you get Red drives if the two you are planning on using aren’t Red drives. It may be okay to use non-Red drives for a month or two but for the long term I strongly recommend not to keep using green/blue/black drives in your NAS if you want the NAS drives to not fail prematurely.

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Thanks for the info. My current drives are WD Green drives, but when I do replace them, I’m planning to get WD Red drives. I’m hoping the green drives will be OK for a few months since they sometimes ship with the My Cloud Mirror version of the product.

As far as I know and have seen, the green drives are ONLY shipped in the cheaper (and really crappy in my opinion) product, single-drive My Cloud. The EX2/EX4/Mirror diskful editions ALL ship with Red drives. I have asked a couple people months ago in the Mirror sub-forum and they all said it was the red model (after they ran hdparm info). But it’s good that you are planning to only use the Green drives for a few monthsand replace them with Reds. Hopefully no longer than 3-4 months.

I had 2 4tb that i had to transfer over to 2 new nasware 3.0 4tb drives…

when i did it… it said ready to rebuild the newly inserted drive… and proceeded to rebuilt the source drive… thus erasing my original information and ruining my raid resulting in data loss…  be extremely careful if you are trying to plug in new drives - i would suggest storing it somewhere else like to a cloud first online and than after you get new drives in and running in the correct mode go ahead and bring your data back to them.

if you cannot manually tell it what drive to mirror to the other drive i dont know the value of this - but dont trust that its rebuilding a new drive when it will just pick whatever drive it wants it seems.