To add to Victor's response, for someone else that might read this and did not have the foresight to build the VM bigger at the start.
In the ArubaOS VM documentation, there is a section on how to increase your flash disk size, so resizing can be done after the fact.
If you do upgrade the flash after the fact, the procedure has you create a new disk, the ArubaOS will see the first disk SCSI 0:0 and the 2nd disk 0:1 as the current drives. It will see the new disk SCSI 0:2 as new, and copy the files from SCSI 0:1 to SCSI 0:2.
The direction then tell you to delete the original disk, SCSI 0:1 (please follow the procedure, not my notes here).
After the original disk is deleted, the SCSI addresses will be 0:0 and 0:2. You should rename SCSI 0:2 to SCSI 0:1.
If you do not, it will not cause a problem. However, it you were to increase the disk size again in the future by repeating this procedure, you would have SCSI 0:0 and SCSI 0:2. If you were to create a new bigger disk, it would become SCSI 0:1. When you reboot, the MM will see the first two disks as the current system, SCSI 0:0 and the new blank SCSI 0:1, and your system will boot as if it has never been set up because the new SCSI 0:1 doesn't have any config. Don't fret, SCSI 0:2 should still be there (and of course you backed up your flash and snapshotted your VM).
I hope this helps,