We're seeing disk drives of various capacities, speeds and form factors, and this can lead to confusion. For example, most enterprise drives shipping today are 3.5-inch form factor using SAS, SATA, Fibre Channel and even traditional PATA) disk interfaces. The problem is that not all 3.5-inch disk drives are high-performance drives. Some are high capacity SATA drives, some are high performance 15,000 revolutions per minute Fibre Channel or SAS drives. Enterprise high-performance small 2.5-inch form factor drives are also appearing, and this is also causing confusion. Traditionally, the 2.5-inch drives have been used in small devices, like desktops and laptops/notebooks, but a new generation of 2.5-inch 10,000 to 15,000 rpm high-performance SAS drives is available. Form factor is no longer indicative of technology or performance.
And more improvements are on the horizon. As the drives get smaller, they can spin faster while putting more data in the smaller footprint -- this translates to larger capacity and better performance. But, hard disk drives are also reducing their power consumption with multiple power settings and adding other functions, such as encryption at the drive level. The recent introduction of "hybrid drives" add significantly more memory to complement the mechanical drive, effectively caching more of the drive's data to memory and allowing the mechanical device to power down more frequently. For example, some drive vendors are releasing 32 GB or 64 GB SATA drives with flash memory only (solid state). We're also seeing variations that combine physical disk with flash or RAM memory. For example, Seagate Technology released a drive in 2006 that combined all three elements -- think of it as real "tiered storage" right on the disk drive itself.
Another innovation is referred to as "sleepy drives" that throttle back the revolutions per minute, reduce power consumption or otherwise power down to some extent when not being used. This technique reduces power consumption, which saves money and can improve battery life in laptops or other mobile devices.
Some experts expect magnetic hard drive technology to remain viable out to 2015 or even 2020.
Go back to the beginning of the Disk Hardware FAQ Guide.
This was first published in May 2007