Some of the original NetApp AFF (All Flash FAS) platforms are reaching the age where one might consider headswapping them. One of the first things we check before any headswap (this was the same for 7-Mode headswaps) is that the root volume is of sufficient size to support the new platform, and if the root volume is too small, we make it bigger before commencing the headswap.
The AFF8020 / AFF8040 / AFF8060 / AFF8080EX have min. root volume size of 350 GiB.
The AFF A200 / A300 have min. root volume size of 350 GiB.
The AFF A700s / A700 have min. root volume size of 934 Gib / 962 Gib.
So, if you want to headswap to an AFF A700s / A700, and you had ADP RD2 partitioned root aggregates, and the root aggregate size is less than the minimum root aggregate size - which is 1 TiB - for the AFF A700s / A700, then you might need to add more disk so can you can create a root aggregate big enough to hold the root volume.
Image: HWU for NetApp AFFs with ONTAP 9.3P7-P9