Replace 2 of 4 RAID0 disks and change those 2 to RAID1

[Niklas_i]

Hi all! I'm new to this forum and generally doesn't have much knowledge about network storage, RAID or the ReadyNAS etc at all, so please bear with me if this seems dumb...

Sorry in advance for the wall of text, and I would really appreciate it if you read my questions and tried to help me 😃

However:

I have the ReadyNAS Ultra 4 with RAIDiator 4.2.31.

In it there are 4 disks with a volume each (i.e. no free disk slots: C (a 2TB disk), D (1TB), E (1TB) and F (3TB), all are RAID0 (single disks). This have been working fine for me since not much important data was actually stored on it.

I have however been starting to store my photos and similar important files on it when the data amount got too large for other local storage solutions. So now I have decided to create a RAID1 with 2 new 4TB disks to get a disk redundancy, and I want to replace the D and E disks to do this. 

The tricky thing (at least for me..) is the question wether I can do this without losing any data? I have very Iimited storage capacity in other places, so I'm gonna have to shuffle the data around a bit between the disks. I also want to rearrange the data into a more structured way.

The only really important data is on the F disk, but I would also prefer keeping the other less important data on the other disks if possible.

I was thinking to approach it like this:

1: Remove disks D and E.

2: Add the 2 new 4 TB disks and configure them to RAID1 with RAIDiator.

3: Move the data from volume F to the new RAID1 volume so F gets empty.

4: Move some of the data from volume C to the new RAID1 volume as well, then rest of C volume to F. 

5: Remove disk C.

6: Add the D disk and move the data on it to F.

7: Remove D disk again and replace it with the E disk.

8: Move the data on E disk to the F disk.

9: Lastly replace disk E with disk C.

The structure I want after this would be:

2x 4TB disks in RAID1 for important data (the new RAID1 volume)

1x 2TB disk RAID0 (single disk) for unimportant data. (the C volume)

1x 3TB disk RAID0 (single disk) for unimportant data (the F volume)

Now for my questions:

1: Is it possible to do it like this, or is there a better way? I realize it's of course better to reconfigure the NAS to the way I want it to with empty disks, but since my other storage capacity is just not that good I probably need to mess around like this. I know this operation will probably take a few days.

2: Can I remove the D and E disks just like that and the data will still be intact after reconnecting the disks to the NAS again in another disk bay?

3: Can I change the RAID level of the 2 new disks to RAID 1 without any trouble, i.e. have different RAID modes on the disks in the NAS? I'm guessing this would be the FlexRAID mentioned in various places? Also I'm guessing I can select RAID1 when creating the new volume in RAIDiator, but I'm not really sure.

4: Should I do the removing/reconnecting of the disks while the NAS is still on (hot swap?) or is it better to reconnecting disks while NAS is powered down?

5: Would it be better/safer to remove all disks from the NAS, add the 2 new in RAID1, then connect the remaining disks internally to a computer and copy the data from the disks in the computer to the NAS, then add empty disks as single disk volumes to the NAS? 

Could there be filesystem mismatches or other issues with this approach? The computer is running Windows 10 if that matters.

I think that was everything I'm concerned of. Thank you very much for reading and I appreciate if you shared some knowledge or opinions with me!

[StephenB]

I think you are making this way to complicated.  You want to destroy volumes D and E, then remove those disks.  Then insert the two new drives, and create a new RAID-1 volume. 

You can get a USB adapter and then save the current contents of D and E to one of the new drives temporarily (connecting it to a PC). 

Then destroy the two volumes,

insert the other 4 TB drive as RAID-0

restore the data from the temporary backup

insert that second 4 TB drive and add it to the first for redundancy.

[Niklas_i]

Thanks StephenB, that sounds like a better idea.

Making things too complicated seems to be something I like to do, unconsiously...

I'll probably try as you suggested, but for now I actually signed up for some cloud storage service, and am currently uploading tons of files to it. I'll report back when the actual restructuring starts in case anyone else have the same thoughts.