I worked for a few years on storage at HP. They had the EVA, 3PAR, and Lefthand product lines when I was there. Though HP sold them as storage array hardware, t

I worked for a few years on storage at HP. They had the EVA, 3PAR, and Lefthand product lines when I was there. Though HP sold them as storage array hardware, the primary expense was engineering the software, not the hardware. The EVA was a storage array that originally came from DEC and ran a custom RTOS. 3PAR and Lefthand both ran Linux. These were large, reliable software products with big install bases. The EVA was over 100k units. I think there were 60-80 developers working on the EVA across 4 sites at the peak. They would also have lots of software engineers working on their networking products. Other operating system software than HP-UX would be VMS and NonStop.