Sorry again my friend, but is not possible to remove disks from an aggregate.
In this case, you need to backup your FAS2040, detroy your aggregate, remove disk ownership from your disk shelf, attach your disk shelf at your new FAS22xx, assign disks for your FAS22xx, create a new aggregate (in this case with internal + external drives because FAS22xx can turn a disk shelf in case of an new upgrade) and restore your data volumes.
Just on more question. On new FAS22xx you said that I should create a new aggregate with internal + external disks. Should I create an aggregate with just internal disks to avoid the same problem that I having now if I want to move disk shelves to another system? Or because FAS22xx can turn internal disks in a disk shelf I should create the aggregate like you said?
Re: Transfering Disk Shelfs from FAS2040 to FAS2240 WITH data