Komag ( KOMG) slashed earnings and revenue guidance Wednesday, adding its name to the long list of computer storage suppliers that saw demand fall off in the second quarter. The San Jose, Calif., company expects to earn 27 cents to 30 cents a share on revenue of $101.4 million in the quarter, with operating margins a lower-than-expected 8% or 9%. Analysts surveyed by Thomson First Call had been forecasting earnings of 35 cents a share on revenue of $105.1 million. Komag, which makes the thin film that records data on disk drives, cited lower-than-expected shipments. The explanation echoes statements throughout the storage space, including warnings from Quantum ( DSS), Storage Technology ( STK) and Maxtor ( MXO). Komag was recently down 98 cents, or 8%, to $11.15 in premarket trading.