Upgrading My Cloud Mirror - new HDDs

I intend replacing the HDDs of My Cloud Mirror. Now I have 2 HDDs 3TB each, but I want to replace them with 4TB ones. Can I do it by first replacing only one of the drives and uploading the information on it and afterwards replacing the second one. The problem is that I use the drives on RAID1. Maybe I will have to replace the both drives, make the RAID1 and after that upload the files from one of the old drives from a PC.


I think it will be better if you take the data out of the drive and then replace the internal drives. If you replace the drives one at the time, you might lose 1TB on the 4tb drives.

But what if I want to upgrade from 2x4TB to 2x6TB. I personally have little chances to store the amount somewhere else and than do a clean upgrade.

Thanks for the replies,
“INGMARPETERS” - you don’t need to store the information on a PC in order to upload it again on the upgraded My Cloud Mirror. You just have to connect one of the old HDDs to a PC and transfer the data directly to the new drives (which are already installed on the MCM).