DS920+ storage pool expansion - issue

[fropdaddy]

I have a DS920+ running DSM 7.
I am running SHR with 3 drives:
5 TB
14 TB
14 TB

I was able to acquire a 12 TB drive and was going to expand my SHR, however I found out in the fine print that you can only replace or expand a SHR drive set with a drive that is equal or larger than the largest drive in the drive set...
This means that the only way that I can add this drive to the drive set is by remaking the drive set which would clear all the data on the drive set (and possibly all the settings on the NAS).
I would be able to borrow a DAS, connected via USB to the DS920+, that would be large enough to copy everything over so that I could remake the drive set.  Is there a way to do this and be able to keep all of my settings and permissions so that I don't have to reconfigure all of the backup clients, plex logins, etc.?
For clarity, could I back up the NAS via the USB port on the 920 to a DAS (exFAT most likely), remake the SHR with the added drive, then restore all the settings and media?

Or is there an easier way to accomplish this?

[ed]

You only need to replace the biggest drive if you want to gain more storage space.
In your situation, you could use the empty bay to expand to add this drive. But it will be seen as big as 5TB or so if merged to existing RAID. You can also set it up individually in basic mode to have full 12TB available.
Here is how
https://kb.synology.com/en-uk/DSM/help/D...?version=7
You can play with the capacity calculator here https://www.synology.com/en-uk/support/RAID_calculator

[fropdaddy]

You only need to replace the biggest drive if you want to gain more storage space.
In your situation, you could use the empty bay to expand to add this drive. But it will be seen as big as 5TB or so if merged to existing RAID. You can also set it up individually in basic mode to have full 12TB available.
Here is how
https://kb.synology.com/en-uk/DSM/help/D...?version=7
You can play with the capacity calculator here https://www.synology.com/en-uk/support/RAID_calculator

I'm trying to add a drive to the 3 drive SHR set.  I am not able as the 12 TB drive is smaller than the 14 TB drive which isn't allowed.
I am willing to destroy the 3 drive set and initialize the 4 drives together into a 4 drive set.  Is there a way to transfer the data via the onboard USB 3 port to a raid tower and then remake the drive set while keeping all of the permissions, etc?

[ed]

You only need to replace the biggest drive if you want to gain more storage space.
In your situation, you could use the empty bay to expand to add this drive. But it will be seen as big as 5TB or so if merged to existing RAID. You can also set it up individually in basic mode to have full 12TB available.
Here is how
https://kb.synology.com/en-uk/DSM/help/D...?version=7
You can play with the capacity calculator here https://www.synology.com/en-uk/support/RAID_calculator

I'm trying to add a drive to the 3 drive SHR set.  I am not able as the 12 TB drive is smaller than the 14 TB drive which isn't allowed.
I am willing to destroy the 3 drive set and initialize the 4 drives together into a 4 drive set.  Is there a way to transfer the data via the onboard USB 3 port to a raid tower and then remake the drive set while keeping all of the permissions, etc?

Yes, you could use Hybrid backup to copy al data and configuration to your USB RAID box. You can then restore the backup on your new volume.
I remember older DSM allowed adding a 4th drive to an existing 3 drive SHR even though the size was smaller on the drive. They must have changed this.