Zyxel NSA325v2 2x8TB in RAID1 possible?

doktor

Hi!

I have a Zyxel NSA325v2 with firmware V4.81(AALS.1) running in RAID1 with two identical 4TB hard discs. I want to upgrade the RAID1 array to 8TB (=2x8TB) in RAID1 mode. I understand there is a compatibility list which guarantees the compatibility of certain hard drives, but only up to 6TB. Is there any experience out there with somebody having gone beyond 6TB? What make of hard drive would be suggested? Are there specific types to be avoided? Is it impossible to go beyond 6TB anyway?

Thanks!

#NAS_August_2020

Mijzelf

That compatibility list is actually a 'known working' list, as that were the disks they tested. There are no 'known not working' disks, and I believe this means all tested disks worked. Which is not strange, as sata is sata. Every sata disk is supposed to work.

I have no experience, but I would expect any 8TB disk to work, and I would choose for low power, and if that matters for you, low noise.

If you want to go bigger, you can expect problems when you go beyond 16TB, as the used filesystem (ext3) doesn't support >16TiB, and I don't think the firmware will have tricks to solve that, by using only a part of the disk. That filesystem limit is also a limit for raid0. 2 10TB disks in raid0 is also a nono.

Mijzelf

The limit is the filesystem size, which is the size you see in the webinterface. So a 2*8TB raid1 array is 'only' 8TB. A 2*8TB raid0 is 16TB (which is still a bit smaller than the max 16TiB.)

Mijzelf

No. At sata level the only difference is that the SMR disk is a bit slower in writing. Maybe not even noticeable in that NAS, as the sata bus speed is CPU limited.

The (software) raid manager can handle a difference in speed between both disks.

Mijzelf

That compatibility list is actually a 'known working' list, as that were the disks they tested. There are no 'known not working' disks, and I believe this means all tested disks worked. Which is not strange, as sata is sata. Every sata disk is supposed to work.

I have no experience, but I would expect any 8TB disk to work, and I would choose for low power, and if that matters for you, low noise.

If you want to go bigger, you can expect problems when you go beyond 16TB, as the used filesystem (ext3) doesn't support >16TiB, and I don't think the firmware will have tricks to solve that, by using only a part of the disk. That filesystem limit is also a limit for raid0. 2 10TB disks in raid0 is also a nono.

doktor

Dear Mijzelf, thank you for your answer. So, when you say "If you want to go bigger, you can expect problems when you go beyond 16TB" I suppose you are referring to 2x8TB regardless of RAID? Since I am only interested in RAID1, to make things straight, in your opinion the safe limit is 2 disks of 8TB each or 2 disks of 16TB each?

Mijzelf

The limit is the filesystem size, which is the size you see in the webinterface. So a 2*8TB raid1 array is 'only' 8TB. A 2*8TB raid0 is 16TB (which is still a bit smaller than the max 16TiB.)

doktor

It appears that it is easier to get ones hands on SMR disks these days. I am not sure about my existing hard disks but they are probably CMR (I bought them around 2014). Do you think there could be a problem during rebuilding the RAID1 array? I mean, the first move is to remove one of the old drives and put in the new one and rebuild the array. During this process one drive will be SMR and one drive will be CMR. Could this cause a problem?

Mijzelf

No. At sata level the only difference is that the SMR disk is a bit slower in writing. Maybe not even noticeable in that NAS, as the sata bus speed is CPU limited.

The (software) raid manager can handle a difference in speed between both disks.