HANA appliances must be certified and come either as pre-built appliances from your vendor of choice or as a custom build using your storage and networks “Tailored Datacenter Integration” or TDI.
SAP maintain a list of certified hardware platforms which currently includes Cisco, Dell, Fujitsu, Hitachi, HP, Huawei, IBM (Lenovo), NEC and SGI, and is being extended all the time. Note that this list only contains the new “Ivy Bridge” appliances and not the older “Westmere” appliances.
The exact hardware and storage configuration varies depending on a vendor. Some use servers and other use blades, some used a SAN storage network whilst IBM uses local storage with the GPFS distributed file system. In our experience, all these variants work very well.
In addition you can buy HANA in the cloud from Amazon, SAP and various other outsource partners like T-Systems or EMC. In this case, you can either pay a monthly subscription fee including license, or use an existing Enterprise license “Bring Your Own License”.