Adding disk to existing SHR Storage Pool

[Evthymios]

I have a baremetal XPEnology running latest DSM 7.1.1. When I installed from scratch (using ARPL), I started from 8 TB disk (an Ironwolf Pro) configured as a single-drive SHR storage pool (with 1 volume). After some time, I bought a second identical 8 TB disk, the DSM detected it and offered me to add it at the existing storage pool, upgrading it into a two-drive SHR storage pool (same 1 volume).

 

 

According to the Synology RAID Calculator, using SHR, I should be able to have several disks with different sizes (only that if a disk is larger than - in my case - 8 TB, the extra space would be wasted/unused). Concretely, I have an unused 2 TB disk (a WD Black) which I would like to add to this pool. The Calculator states I should be able to use a 8 TB disk as parity drive, and 8 TB + 2 TB (a total of 10 GB) as storage drive.

 

 

But if I try to add the 2 TB drive to the existing pool, I receive an error: "The requirements for drive size are not met" - Drive capacity should be >= 7.3 TB.

 

 

What am I missing? According to the Synology Calculator (at least if I understood it correctly), it should work...

Edited April 19, 2023 by Evthymios

[dj_nsk]

42 минуты назад, Evthymios сказал:

The Calculator states I should be able to use a 8 TB disk as parity drive, and 8 TB + 2 TB (a total of 10 GB) as storage drive.

This would be the case if you were creating a new resource pool. But when you add a new disk to an existing pool, then "The capacity of the drive you wish to add must be equal to or larger than the smallest drive in the storage pool"

[Evthymios]

So what options do I have? Delete pool and start from zero? Or are there any faster/simpler variants?

[dj_nsk]

3 часа назад, Evthymios сказал:

So what options do I have? Delete pool and start from zero? Or are there any faster/simpler variants?

Yes, this is the safest option. If data and settings are important, then first you need to make a full backup to an external resource, and after creating a pool - restore it from the backup (Hyper Backup). 

Perhaps there are non-standard ways to solve the problem, but they have too high risk of data loss (and if you do a backup, it will coincide with the first option in duration).

After the pool is created anew, it will be possible to add new 2Tb disks into SHR next time.

 

Or create a second resource pool.