Even the most proprietary software generally has open source inside. That's why Gartner analyst Martin Kihn can declare with utmost assurance that everything—everything—is open source now, to some degree:
I am willing to guess you—yes, you—would be shocked if you really understood to what extent that whizzy piece of expensive cloud software you're using actually (deep, deep in its soul) was running on absolutely free, not-developed-here, open source technology that you—yes, you—could probably bang into something almost as useful if you only knew how to do it.
It's also why you really, really shouldn't be futzing with SAP HANA, or any other proprietary data infrastructure that tries to go it alone without the aid of the open source community. Cloudera chief strategy officer Mike Olson perhaps said it best:
Jefe de Cloudera
There's been a stunning and irreversible trend in enterprise infrastructure. No dominant platform-level software infrastructure has emerged in the last 10 years in closed-source, proprietary form.