This doesn't seem to be an issue with 4.3, but I noticed that in 4.2 we have hard-coded the max custom disk offering size to 1024. I'm going to fix this (assuming we ever release a 4.2.2), but the use of 'final', and the fact that the min size is already set up to be configurable, made me think that this was probably done with intent.
server/src/com/cloud/storage/VolumeManagerImpl.java: private int _customDiskOfferingMinSize = 1; private final int _customDiskOfferingMaxSize = 1024; Can anyone think of why?