WD MyCloud Mirror - Expanding Storage by Replacing HDD

Hi guys, I got a response from one the members of the community and I really appreciate it. I learned that MyMirror cloud can increase its storage capacity if I change the HDD itself. Currently its 6TB and i would like to increase the capacity to 12TB by replacing the HDD’s.

My question now is… how? Should I remove the 2 HDD and place it with new ones just that or I just have to replace only 1 but which one?

If there’s anyone who knows I would appreciate the tips. Thanks so much!

It depends somewhat if you want to keep the content of the existing drives or not, and also how they are set up (RAID0, RAID1, spanning or JBOD).

If it’s in the standard RAID1 and you want to keep the content, change one, let things rebuild (copy from the old drive onto the new one) and then change the other and rebuild again to the new full set-up.

If it’s RAID0 or spanning then change both at once, as the drives are being used as a pair and won’t work individually.

If it’s JBOD then it doesn’t matter, as the drives are running independently anyway. If you want to keep the stuff then change one, copy across internally then pull both, repeat and then put the two new ones in together and away you go.

There’s some details on physically how to go about doing the drive exchange in the manual.


thanks Darren its really informative. physical aspect no worries about it. my hands are itching to try it out. my worries is the software part which you have clearly states.

thanks again have a good one.

“If it’s in the standard RAID1 and you want to keep the content, change one, let things rebuild (copy from the old drive onto the new one) and then change the other and rebuild again to the new full set-up.”

My uderstanding is that you cannot increase the capcity of a raid 1 array by increasing the size of one of the drives. If you want to replace your 2x3GB drives with 2x6Gb drives, just take them out and replace them. The Mycloud mirror will set up the drives in the setup routing. If you want to copy your existing drive content to the new drives, you will first need to copy then to a different device (network or USB drive), replace the drives with the new drives, and then copy the files back from your temporary storage device.

yea its a standard RAID 1. So i guess I have to replace 2 drives. and theres a setting “Auto Rebuild Raid System”. So i think I have to turn this on so if I replace the 2 drives it will rebuild itself.

Thanks guys!

Replace the drives, select RAID 1 and then copy the files you temporarily stored on your external backup back on to the WD MyCloud. You can’t avoid the external backup phase.

Not true : the external backup is optional. Go to >Storage>RAID Mode and if you are RAID 1 there is a check box “expand capacity”, which will guide you through the process. Mind you, take out a full day for this job, and a weeks worth of patience. Also, for ease-of-mind a full copy of the content on an external drive seems like an awfully good idea.

I wanted to share my experience with this. I replaced two 3T drives running RAID1 with two 4T drives using the WD EXPAND option on RAID1. It was straight forward. The software prompts you to remove drive 1 and replace it with the larger drive. After moving the data, it prompts you to remove drive 2 and and insert the second larger drive. When complete I had a 4T RAID1 drive. My 3Ts were 7 years old and the data is important to me so I replaced them. I’ll put one of the old 3T drives away in case something bad ever happens to my data and the other I’ll use for less critical data backup. These Red Drives have been running 24/7 for 7 years without a problem. I am impressed.

Curious whether you researched capacity restrictions with the replacement HDDs. I currently have 4TB drives and am looking to upgrade to 10TB drives. I’m worried whether or not the My Cloud Mirror can handle/support this size drives. Thanks!

Yes, it can. But the Gen 1 MCM is an old, old device. You will find many limitations. You might want to consider updating to a Synology or QNAP.