NAS Expansion?

[Enquiries]

I have a Synology DS2413+ with 10 x 6TB WD SMR drives (4.5 yrs old) and 2 x 2TB WD Desktop drives (8.8 yrs old) running RAID in SHR-2. I have slowly been replacing the 2TB drives as I've required more space. I'm currently at 43TB used of 47TB available space so I'm looking at replacing the 2 x 2TB drives.

Note: I understand SMR and CMR drives and the problems with NAS so please ignore for this question.

I would like your opinion on the following solutions:-

Replace the 2 x 2TB drives with 2 x 6TB WD SMR drives to make 60TB, or about 55TB usable. Then add an external 12TB WD MY Book drive and Archive out unused files. This way I can get 72TB of storage for about $900 AUD.

Replace the 2 x 2TB drives with SHUCKED 2 x 6TB MY BOOK drives (with PIN 3 covered or removed). Then add an external 12TB WD MY Book drive and Archive out unused files. This is the cheapest way I can get 72TB of storage. About $780 AUD.

I have also looked at replacing the 2 x 2TB drives with larger CMR drives but will need 4 12TB drives to get to 72TB because of SHR-2. This becomes expensive. 4 x 12TB SHUCKED MY BOOK drives will cost $1,500 AUD. 4 x 12TB WD RED PRO would be $2,500 AUD.

Using external Archive drives seems the way to go but is this a reliable solution?

[ed]

You can offload some data to external drives. Just make sure they have a backup or RAID protection just in case. These USB connected drives will not expand your NAS storage and you will not have access to this data in a normal way via mapped drive (only via DSM admin panel).In meantime, you can add any drives you to your NAS. It will work. It is just recommended to stick with the same kind of drives due to performance purposes. Simple file storage might not need this though.I hope this helps.