Red Hat Linux (RHEL) is now also certified by SAP for HANA.
If you look at the overall breakdown of certified appliances Red Hat operates with
RHEL 6.5 (200)
RHEL 6.6 (437)
While SuSe Linux SLES operates with:
SLES 11 SP1 (27)
SLES 11 SP2 (8)
SLES for SAP SP1 (32)
SLES for SAP SP2 (73)
SLES for SAP SP3 (696)
When SAP was developing the product it worked exclusively with Intel to tune the physical compute chip instruction set to HANA it also worked exclusively with SuSe to tune the operating system to support HANA. Since HANA's release others, Red Hat for operating systems and IBM for its Power architecture running AIX, have worked with SAP to get HANA certified on their products.
Red Hat has been successful and as you can see above represents an almost 50/50 split for the customer base and remains a primary force in the commercial Linux marketplace.