A new minimum configuration for SAP HANA (IMDB) licenses are available, this new minimum is 64GB. Larger configuration must be purchased in 64 GB increaments to align with supported SAP HANA.
All you need to remember HANA Configuration must be minimum of 50% of total size.. of the server on which it resides. e.g. 128 GB of HANA can run a 256gb Server, but i cannot run on 512 GB or 1 TB.
in terms of CPU/memory there is not much difference All the Servers from any vendors are having same processor.. (Nehlam 2.26) for all the vendors HP, Fujitsu, IBM, Cisco or Dell.
It's not as simple as 4 TB = X TB in HANA.
In general the compression depends on the sparsity of data. Typically the compression rate is anywhere between 1-10x. So if you wanted to put your whole BW database in HANA you would need roughly about 800 GB of memory (assuming an average 5x compression rate). On top of this you also need memory for processing which is estimated to be roughly double. So I would guestimate you would need 1.2 TB of memory.
RE: CPU - There are still no guidelines on CPU, but this is usually not the bottleneck.