For the first time last year, it became possible to buy an ATA disk drive with more capacity than a SCSI drive. Also for the first time in 2002, the average SCSI drive sold with less capacity than an ATA drive -- SCSI's 36 GB to ATA's 40 GB, according to David Reinsel, research manager at IDC.
Today, the capacity difference between the two drive types is even more pronounced, with ATA drives shipping with two times the capacity of the highest capacity SCSI drive -- for example, Maxtor's 320 GB drive, as compared to Seagate's 147 GB Cheetah 10K.6. Seagate recently discontinued its 182GB Barracuda 180, a 7200 RPM drive.
"The Barracuda 180 was the last SCSI drive to have a capacity advantage over ATA drives," says IDC's Reinsel. Now that that's happened, drive manufacturers "don't need to keep that race up."
Instead, manufacturers can now emphasize their drives' performance characteristics. Maxtor may have a 320 GB drive, but it's only 5400 RPM, as opposed to the Cheetah 10K.6's 10,000 RPMs, for example. According to Seagate spokesperson David Szabados, "15K is more and more becoming mainstream in the enterprise while 10K is the entry-level speed desired."
Furthermore, when it comes to making a fast drive, "having a lot of capacity all under one spindle isn't necessarily a good thing," says John Monroe, a vice president at Gartner. In high-performance environments, it's preferable to divvy up capacity between multiple drives in order to ensure sufficient throughput.
SCSI drive marketers, however, haven't completely given up on playing the capacity card. If you consider the drive's footprint, the 147 GB Cheetah 10K.6 allows for more capacity than the Barracuda 180, Seagate argues, because it features a low-profile (one inch) form factor, as compared to the Barracuda's half-height size, at 1.6 inches.With more and more servers and arrays calling for low-profile drives, the half-height Barracuda took up the space of two low-profile drives, limiting the total capacity possible in a given space.
Whatever the case, it's doubtful anyone will miss the late Barracuda 180. In 2002, Reinsel estimated that the Barracuda made up "well less than 5%" of SCSI and Fibre Channel disk drives sales in 2002. Overall, the segment was dominated by sales of 36 GB and 18 GB drives, which garnered 40% and 39% of the market, respectively. The remaining 16% or so are carved up among 9 GB, 73 GB and 147 GB drives.
For more information:Featured tip: Serial ATA: Here, now
Expert advice: Killer serial: is ATA ready for the enterprise?
Advice: Should ATA disks become a standard for online data?
Sign up for your free copy of Storage magazine here.