Hitachi has continued its my-hard-disk's-bigger-than-yours fight with Fujitsu with the announcement of a 400GB, 3.5in drive. The Deskstar 7K400 is the highest-capacity 3.5in ATA drive and spins at 7,200rpm.

The 400GB drive announcement comes just a fortnight after HGST announced a five-platter 300GB drive, which it proudly stated was the highest-ever capacity, enterprise-class hard drive ever built.

However, main rival Fujitsu wasn't going to stand by and watch Hitachi claim to be the best. So this week, it announced the Fujitsu's 300GB enterprise drive. Not only was this the same size, it was a four-platter unit, which meant lower power consumption and a higher data rate than Hitachi's offering, execs fired back.

Now Hitachi has gone one better.

The new 400GB drive also uses five platters. It is designed for audio-visual use, for example in digital video recorders, and for nearline storage. HGST says both need large capacities and a low cost per GB. It has parallel and serial ATA interfaces and uses the spindle motor used in HGST's enterprise-class drives. There is an 8MB cache and a 4.17ms average latency, five platters and ten heads. The areal density is 61.7Gbits-per-square-inch.

Fujitsu's 300GB MAT drive has an areal density of 75Gbits-per-square-inch and spins its platters at 10,000rpm. It has SCSI and Fibre Channel interfaces.

Gerard Marlow, business development manager for Fujitsu Europe, grumbled: "The Hitachi drive is a desktop drive through and through." Because it's not an enterprise-class drive it takes a hit on performance and reliability. "For nearline storage, reliability and performance is not so important as with enterprise-class drives," he scratched.

Fujitsu has no plans to slow its MAT drive down and so enable higher capacities, Marlow says. "Fujitsu's game is to play in the enterprise segment and not the desktop segment."

This latest round in the HDD capacity stakes leaves Maxtor, Seagate and Western Digital quite a long way behind.