Hard drives get smaller - part 1

The 3.5" form factor hard drive is a standard across desktop, server and enterprise systems. Not so in notebooks where the constant pressure to lighten weight, lessen power needs and reduce physical size has encouraged the development of 2.5 inch drives.

The relatively recent consolidation of disc drive suppliers has left Maxtor, Seagate and Western Digital as the main suppliers of 2.5 inch drives and they have their individual strengths in external vs internal, desktop vs server, and ATA and SCSI interface standards. There are three main Asia-based drive suppliers: Fujitsu; Hitachi Data Systems (HDS); and Toshiba.

As area densities continue to increase the number of files or data base records on a drive increase as well, increasing the likelihood that more than one file or record will be needed at once from a drive. We might imagine that a 500GB drive might have a 500 times greater probability of simultaneous I/Os than a 5GB drive. Drive I/O performance is measured in I/Os per second or IOPS. Moving to smaller drives will mean fewer files or records per drive and, on the face of it, avoiding hitting an IOPS bottleneck.

Another factor encouraging the emergence of a new cross-system standard form factor is manufacturing efficiency. A standard form factor means that product lines can be switched between PC, server or enterprise drives, between different spin speeds or different interfaces comparatively easily. Coping with multiple form factors makes this much harder. Such manufacturing efficiency could lower drive prices.

Seagate and Fujitsu appear to be leading an initiative to persuade us to purchase 2.5" small form factor (SFF in Seagate acronymics) drives because of these factors. There is also the supplier competition angle that, if they are successful, we'll buy these drives from them rather than from Maxtor or Western Digital who will be late to this market.


Fujitsu Computer Products of America announced recently that Hewlett-Packard was testing its 2.5-inch Serial Attached SCSI (SAS) drives. The shrunken size of the models helps manufacturers increase the data storage capacity in their products, according to Fujitsu. The drives, which can hold up to 73.5GB of data each, are about a third of the size of the 3.5 inch drives typically used in storage systems. So you could put six of them in the space taken up by two 3.5 inch drives.

Also, since a 2.5-inch disk platter contains less mass than its 3.5-inch counterpart, the drive can be spun at lower power, generating less heat. Some manufacturers have re-purposed 3.5-inch chassis to house the 2.5-inch platters, but Fujitsu's new drives shrink the form factor to about the size of the 2.5-inch drives, a 70 per cent reduction in size.

The Serial-attached SCSI (SAS) interface is used and Fujitsu said its SAS drives 2.5-inch SAS drives can transfer up to 300MB of data per second.


Seagate had no notebook computer HDDs in its product line-up until June 2003. Then it introduced its Momentus notebook drive line, offering 20 and 40GB capacities in a one-platter design. The company said it is the only independent maker of notebook drives, meaning that Toshiba, Fujitsu and other build their drives for their notebooks. The claim doesn't mean much for us notebook users; it's germane to notebook manufacturers though, as Fujitsu is hardly likely to second source drives for its notebooks from notebook competitor Toshiba. Also HP might feel it will get a better response from a non-notebook manufacturing drive supplier, such as Seagate, for its own notebook manufacturing needs.

Seagate said its drives rotated at 5400rpm, faster than the then standard 4,200rpm, but didn't need any more power so battery life was unaffected although the notebooks performed faster. Tests showed that Momentus drives are 47 per cent faster at opening a 12MB Excel file, 30 per cent faster at copying a 170MB folder, and 47 per cent faster at shutting down Windows XP than the traditional 4200rpm notebook drives. With an 8MB cache option, the drive performs up to an additional 15 per cent faster.

At the time, Dave Reinsel, research manager at market research firm IDC, pointed out that, "The market for notebook hard drives is growing faster than the PC or the enterprise hard drive market, and will reach 50 million units in CY04." We're all buying more notebook computers and needing more drives. Acer and HP indicated that they would use the Seagate drives.

Enterprise Applications

Seagate is trying to persuade us all that there is an enterprise application for such small form factor drives. Here is an example of its evangelical prose; "Seagate is engaging in an unprecedented strategy to address this need, by moving the industry toward a new 2.5-inch enterprise disc drive platform. Systems built around these small enterprise-class disc drives will provide data centres with unparalleled levels of IOPS (input/outputs per second) performance in a smaller system space compared to what's being delivered today"

What both Fujitsu and Seagate are considering is that blade servers will need blade storage cards as well. We are looking forward to bladed racks which offer complete server and storage farms in a rack. Only the 2.5 inch form factor can populate these arrays to a high enough capacity level and offer the IOPS levels needed. Up until now Maxtor and Western Digital have made no public utterances on this topic. That can be expected to change in 2004.