How to upgrade HDD capacity WD MC EX2100

Hi,
have a question. I have a WD MC EX2100 (2x4TB)in RAID 1. Now I´m running out of space so I´m wondering how to upgrade the HDD from 4 TB into 6TB without loosing my original data. I was thinking that since in RAID 1 more the data are mirrored I can maybe replace one of the 4TB HDD(let´s say from slot 2) and put the new 6TB HDD into slot. The unit will restore the RAID 1 and so copy all the date from slot 1 into slot 2 right ?Once this done I can maybe replace the HDD from slot 1 also with new 6TB HDD and the proces will run again to restore RAID 1. Question is how to use all 2x6TB capacity since tha original RAID was created for 2x4TB. Can someone help ?

David

It will not work without erasing data and making a new RAID volume. The 6TB drive will be mirrored as 4TB since that’s the size of the original volume, which means the second 6TB drive will be treated as a 4TB unit because the size of the volume within the first 6TB drive will be 4TB.

OK but will I abble to expand RAID 1 into 2x6TB once both HDD are changed and mirrored? I mean original RAID is configured for 2x4TB so what exactly shall I do for expand?
How do I do It in Dashboard?

Thanks
David