Citation :
Complications on the road to 3TB
The Caviar Green 3TB makes use of Advanced Format to use the capacity it has available more efficiently. Rather than breaking platters up into 512-byte blocks, Advanced Format relies on 4KB sectors that waste less storage capacity on overhead. Advanced Format is new enough to create compatibility issues with some software, which is why the Caviar Green uses 4KB sectors internally but presents itself as a drive with 512-byte sectors thanks to an emulation scheme WD dubs 512e.
Using 512e is all well and good on drives with capacities less than 2.19TB, but you run into problems with anything larger because Master Boot Record partition tables can only address up to 232 blocks. With 512-byte sectors, that adds up to a maximum capacity of 2.19TB, or considerably less than the 3TB offered by the new Caviar Green. The storage industry's answer to the MBR's addressing limitation is the GUID Partition Table, or GPT, which can address up to 264 sectors. Windows XP doesn't work with GPT partitions, so Western Digital isn't supporting the drive under that OS, although it notes that users may be able to find workarounds using third-party controllers and drivers.
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