Hi,
I’m running a TVS-673 with 5 * 6TB drives in currently, I’m looking to replace these with larger drives (likely 12TB) and therefore won’t need as many drives as I currently have.
I’ve read the articles about drive replacement, however they all seem to refer to replacing ALL the drives, not reducing the drive count.
Is it possible to install a smaller number of larger drives? given the increase in capacity I would probably only install 3 drives to start with.
Hi and welcome to the forum. 
You can’t reduce the number of member drives in an established array.
You would need to build a new array with your new drives, then restore your data into it.
Wait: have you configured your drives as an array? Or are these single drives?
OK, thanks for confirming (and the welcome).
That makes things a bit more complex, I only have the one NAS and there’s quite a bit running on it so a full backup, rebuild and restore is going to be complex.
My TVS-673 is 8 years old, it’s home use so doesn’t get used that heavily. Now I’m wondering if it’s time to consider replacing it and migrating things across.
If you’re using each drive as a single disk, that makes a difference. What is your existing RAID config?
RAID 5 with a hot spare, 4 drives in the array, 1 for the hot spare and an empty slot.I could add a 6th drive but given the shift and price of larger drives, and age of the current ones, it seemed to make sense to upgrade.
Agree, time for a new NAS and drives. 
If you do get a new NAS, you can forego the hot spare, and use your existing NAS to backup the new NAS.
OK thanks, time to browse the QNAP store to see what is available.I run a HomeAssistant VM, Plex and QVR Surveillance with 3 cameras and about 15TB of used storage at the moment. I use 2*M2 SSD’s for the virtual machines.
Any suggestions on a replacement?
I’ve got some external drives connected for local backup, and use hybrid sync into a Onedrive account for the really critical stuff.
I’m not a user of Plex or QVR Surveillance, so I can’t advise on a suitable replacement NAS.
Maybe someone else here can offer an opinion?
Hello,
a TS-464
TS-464 | Bye-bye Gigabit NAS, hello 2.5GbE NAS. | QNAP
But the TS-464 has 2 M2-NMVE-SSD.
The TVS-673 has 2 M2-SATA-SSD. You need 2 new SSD
I would spend as much as you can afford on a new NAS. I purchased a TS-873A (slightly more powerful than the TS-464 @Becker2020 suggested) about a year ago. I wish the TS-873A was more powerful. If you are running QVR Surveillance, Plex, etc, you need a more powerful NAS.
I don’t know your budget - only you do. But get the most expensive NAS you can afford. I would stay away from ARM based units. Buy an x86 NAS.
Sometimes you can find great deals on a used NAS on eBay. I bought a TVS-672XT with drives for $400. The drives alone were worth more than that. I just recently had to have it repaired due to an Intel chip issue with that series, but it was still worth it. Now I’ve upgraded the processor to an i7 and it makes all the difference in the world.
If you want to just share files and do basic NAS functions, the low-end Celeron models are fine. If you want to do more complex things, you need more power.
Regarding your need to reconfigure or change your RAID type, the most straightforward approach is to back up all your data to an external source, rebuild the desired RAID configuration from scratch, and then restore your data.
While online migration is an option, the “Backup-Rebuild-Restore” method is also a way to minimize the risk of data loss and ensure a clean system configuration.