At a time when Seagate is promoting the use of 2.5inch drives as a way of increasing the disk I/Os per unit of rack space, other vendors are introducing 3.5inch whoppers.Both Fujitsu and Hitachi Global Storage Technologies (HGST) have introduced 300GB drives and HGST has even announced a 400GB drive. These drives are aimed at enterprise server applications and have SCSI and Fibre Channel connectivity.

It looks as if the Japanese suppliers have stolen a capacity march on the western trio of Maxtor, Seagate and Western Digital. Disk suppliers say that enterprise class drives are built for 24 by 7 operation and have wider tolerances to increase drive reliability. There will tend to be fewer and wider tracks to increase the head's ability to read and write data signals. The platters will spin at a slower speed so as to reduce vibration and increase the data bit time underneath a head so as to increase signal detection ability. The drive builder will focus on reliability as much as capacity. Up until now top enterprise drives have spun at 7,200rpm and offered 250GB.

In the last couple of years ATA or desktop drives have been positioned as capacity-centric and built for less demanding operation. Their stated duty cycles do not include 24 by 7 operation and it's said that if they are used in such environments they have a greater chance of failing. A new class of server disk use has arisen with so-called nearline storage in which ATA or Serial ATA drives are used in a quasi-desktop fashion to hold fixed content or reference data. Each individual item must be retained with fast access but has little likelihood of actually being accessed. Maxtor has a 300GB MaXLine II spinning at 5400rpm for such nearline applications.

Network Appliance, NexSan and StorageTek (with BladeStore) and other suppliers have all produced SATA arrays for nearline use. We have three classes of HDD for business users. Desktop and nearline for desktop-style drives with partial use and enterprise drives with 24 by 7 use. What Fujitsu amd HGST have done is to push the enterprise HDD capacity envelope.

What do other suppliers think of 300 and 400GB 3.5inch enterprise drives?

Maxtor
Didier Trassaert, VP EMEA at Maxtor, said, "The most popular SCSI/Fibre channel capacity points are 36and 73GB but there are always customers with a need for higher-capacity units." He mentioned space limitations as being a reason not to have, for example, five 73GB drives in a unit.

He confirmed the need for 300GB-class nearline drives and said, "Maxtor continues to be the leader in developing high-capacity, enterprise-class ATA drives designed for nearline ... secondary storage applications." There is also a desktop need for such capacities; "Some desktop users will need ATA/SATA drives with 300GB and even larger, especially as PCs become the consumer's digital home entertainment storage hub."

Maxtor doesn't have an enterprise-class 300GB drive. It intends to push past 300GB capacity though; "The company expects to ship 500GB drives in 2005." It will achieve this through density improvements rather than by adding platters. "Unlike its competitors, Maxtor uses evolutions in aeal density to bring about more capacity with fewer components."

It will be some increase to move from 300GB to 500GB, over 50 percent. We might imagine Maxtor would introduce a 500GB MaXLine-type unit spinning at 5400rpm for nearline work with an enterprise-class unit spinning at 7200rpm with, say, 400GB thus providing the reliability margin needed for enterprise drives. We might also think that a capacity jump from 300 to 500GB is pretty huge and that an internediate level might be introduced first, such as 400GB.

Western Digital
WD won't increase capacity by adding platters either; it currently has a maximum of three. For WD enterprise-class means a spin-speed of 10K, an 80GB platter, and a Serial ATA interface. There have been rumours about a 400GB WD drive. Techworld spoke with Ian Keene, Western Digital's business developer for the enterprise sector.

He added more imformation on enterprise drive reliability; "2.5inch platters are being used by most suppliers to avoid wobble," as opposed to 3inch platters or larger. Regarding desktop capacity he said, "If you can ship more capacity, at a lower cost/GB, definitely there's an interest. We (currently) ship 250GB - it hits the sweet spot."

Will WD move to 300GB? "Yes, we need to get to higher capacities. There are two ways: fit more disks (platters) into the unit; or increase capacity. We ship up to three platters at 80GB/platter." The hint here is that there will be an areal density increase. It means that the same clamshell, motor and basic head/disk assembly can be used with increased density platters. He offered this thought; "May the next stage is 120/130GB per platter to get to 400GB." That would be three platters at 130GB each taking us to 390GB.

Regarding the Japanese suppliers' 300GB moves he said, "Hitachi have done this before; come to market with more heads and disk (platters) to get a lead. In the past it's disappeared. 80GB/platter is not that old."

With Seagate presenting its HAMR areal density increase ideas it seems pretty clear that the main HDD suppliers will all have 300GB capacity enterprise-class drives and that they will move into 400GB nearline drives, possibly in 2005.