Gus,
This is great information, thanks. I didn't realize they went to 3" disks. I don't pay that much attention to their new high-end product announcements, obviously. It's not the area where I work.
Traditionally, "short-stroking" is a term that's been used to describe using only the outer x% of each platter. This has two effects: first, since zone-recorded drives (all drives since about '91) have more sectors per track at the outside, and the spin speed is the same everywhere, average transfer rate improves when you short-stroke a drive. Second, since the radius that the actuator must seek across is smaller, average seek times are lower. The trade-off, of course, is capacity. I've only seen a handful of drives employ this technique over the years.
What Seagate has done is instead make the platter smaller, which effectively uses the inside x% of a 3.5" drive. Sounds like they've got an areal density advantage that allows them to do this without adding platters.
Smaller platters have traditionally been associated with mobile products, where size and weight are critical, but for the last few years there's been a lot of talk in the industry about small platters applied to a high performance design. As far as I know, this drive is the first to do it. It makes a lot of sense for a few reasons. As I mentioned, with no change in spin speed, average seek times improve but average transfer rate decreases when you use only the inner radius of a platter. However, it takes a lot of the pressure off the channel transfer rate, always the limiting factor at the o.d. So a smaller platter can be spun faster, because the channel can keep up at smaller radii for a given bit density. Bottom line: you can spin faster, seek faster, recover much of the lost transfer rate (more if you've got a bpi advantage), and realize a latency reduction.
This is great news, to see Seagate leading like this. I just hope they can translate it to their desktop products, where I maintain they are playing catch-up (and losing). |
