The companies have been strategic partners for more than a decade. A majority of Western Digital's NAND-flash memory is primarily supplied through its business ventures with Toshiba, according to its annual report. It's the most popular rewritable memory chip used in USB drives, cameras, iPods, smartphones, tablets and other devices. Toshiba's global tumult has already spilled into OC, where the tech giant sold its 26-acre campus at 9740 Irvine Blvd. in the Irvine Spectrum in December. The Business Journal in May reported that the company will shutter its U.S. commercial phone service division based in Irvine in its second local business closure in about a year. Toshiba America Information Systems Inc.'s Telecommunication Systems Division employs about 150, putting it at No. 8 among the largest telecom employers here. The cuts amount to about 8.5% of Toshiba's OC operation.