Seagate confirmed on Monday that it does plan to ship a 3TB, 3.5-in Constellation ES hard disk drive this year, but cautioned that it will only be useable with PC and server makers who have upgraded their products to handle drives with capacities of more than 2.1TB.
The 3TB drive is the next generation of Seagate's Barracuda XT, which currently comes in capacities of up to 2TB and has a 6Gbit/sec. throughput and serial-attached SCSI (SAS) interface. The 2.1TB ceiling was set about 30 years ago when a decision was made to limit the logical block address (LBA) range on a hard drive. The LBA specifies where blocks of data are stored on a hard drive.
Seagate senior product manager Barbara Craig said that the new 3TB drive will initially be aimed squarely at the enterprise space, "which is always hungry for more capacity." However, she said that a 2.5-in version is in the works. But Seagate declined to say when that drive, suitable for a laptop, would be shipping.
A 2.5-in drive could also be used in data centers to further reduce floor space requirements. Before that happens, equipment manufactures much make adjustments in order to read new 32 byte LBAs, Craig wrote in a blog post last week.
Software and hardware manufacturers now need to adjust everything from the operating system to the basic input/output system (BIOS) to be able to read larger 32-byte LBAs, Craig said. Without the larger LBA, current operating systems, such as Windows XP, would only be able to access as little as one-third of the space of the new 3TB drive. "It's a big deal," Craig said. "Everybody has to be able to access these longer addresses with their products."
There has already been a lot of work done to date to address the LBA limitation, including the creation of a Universal Extensible Firmware Interface (UEFI), which defines how software interfaces with an operating system and the hardware on which it is running on. Updates to standard hard disk drivers are currently being tested by Seagate and Intel, according to the hard drive maker.
The expanded LBA is also a non-issue for 64-bit operating systems such as Windows 7 and Vista versions, which can already read the longer addresses, she said.
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