Upgrading NAS RAID 1 drives

[scooby]

My NAS is configured as RAID 1 2x1tb (same make and model etc) HDDs. How do I upgrade the HDD to 2tb or 4tb without losing data? Can i just remove one of the drives and it will auto rebuild (this is the set as an option) but how will it handle different size disks when mirroring, or does size not matter?

[SimonMac]

My NAS is configured as RAID 1 2x1tb (same make and model etc) HDDs. How do I upgrade the HDD to 2tb or 4tb without losing data? Can i just remove one of the drives and it will auto rebuild (this is the set as an option) but how will it handle different size disks when mirroring, or does size not matter?

It will only be seen as the size of the smallest drive of the two, if you then add another larger HDD to match I assume it will then give you the full size again