Synology DS423+ expand problem

[pascanu]

Situation:
- had a DS 216+ with 2 x 3TB drives
- got a new DS 423+ and set it up with 2 new 4TB drives in SHR
- when I try to add the 2 old 3TB drives to it it says I cannot because they are too small

I thought you could mix different size drives in a SHR configuration, there's even a SHR calculator that says that with the drives I have I should get a total of 9.1GB storage.

What am I missing?
TIA

[ed]

Not any more in DSM7. You could with DSM6.

[richtheace]

SHR has this issue. You can't add a drive smaller than the smallest drive in the current raid setup.

You could add the two 3TB drives as a new SHR pool/volume, move your data to that new volume.
Then delete the old two 4TB pool/volume.
Lastly, you can add two 4TB drives to the new SHR pool/volume, Giving you about 9TB

PLEASE NOTE: You may also get issues if you don't remove the apps first as the Synology uses Volume 1 as default, and when you make the new pool/volume you will make Volume 2 and this can have funny results with broken apps left installed when volume 1 is no longer there.