The big buzz in hard drives right now is Western Digital's 3TB WD Caviar Green (WD30EZRS) internal drive. Along with its cavernous capacity, the Western Digital Caviar Green 3TB drive boasts a 64MB cache. But what makes it special - at 3TB it's the largest capacity internal hard drive currently available - is also what makes it awkward.
MBR to GPT
If you're using Linux or Mac OS X, you can skip the description of problems that follow. Your operating systems are not affected by these issues. To begin with, some legacy-based operating systems such as Microsoft Windows - including Windows 7 - tend to use a Master Boot Record (MBR) partition table arrangement as their standard.
MBR partition schemes can only address 232 logical blocks on the hard drive with a common sector size of 512 bytes. In other words, the maximum size of volume is 2.19TB of data. The alternative is to use the GUID (Global Unique IDentifier) Partition Table scheme, otherwise known as GPT, which allow for up to 264 of logical block addressing. The file system may still be NTFS in the case of Windows systems, but the partitioning scheme allows for drives larger than 2.19TB.
Unfortunately, we ran into problems when we tried to switch to GPT on a Windows Vista system. Vista offered the choice of partitioning as MBR or GPT the first time through, but then reverted to MBR-only. After a few unsuccessful hours of trying to fix the situation, we simply wiped the system's boot drive and installed Windows 7. Everything worked well after that.
While 32-bit Windows XP systems can't handle GPT natively, there is a solution: Paragon Software Group's Paragon GPT Loader, which is currently free under its early adopter program. This software allows Windows XP computers to use drives larger than 2.19TB. However, there still may be an issue you have to deal with. Not all Windows applications can handle GPT, even on 64-bit systems.
As a result, Western Digital has supplied a workaround: a HighPoint Rocket 620 internal half-height SATA PCI card, which it can sell with the 3TB drive. The card has two SATA 6Gb/s ports and handles the emulation, if needed, to allow software to work with the larger 3TB hard drive.
In order to test whether using a drive under GPT offered disadvantages (or advantages) over a drive under MBR - in other words, to determine if switching the partition scheme for 3TB of space is worth the trouble - we tested the performance of the Western Digital Caviar Green 3TB drive, alongside a 2TB Caviar Green drive (Model WD20EADS), using both the MBR and GPT partition arrangements.
We first partioned both drives as GPT and tested using Simpli Software's HD Tach and Futuremark's PCMark Vantage HDD test. The two drives ran at nearly identical burst speeds, with the 3TB drive marginally faster at average reads (114.9 MB/s versus 86.7 MB/s) and random access (15.6 ms versus 20.2 ms).
The PCMark Vantage results were also virtually the same. The 3TB drive running under a GPT partition table was the performance equal (actually, the slight leader) when compared to the 2TB drive.
Knowing now that the two drives were equivalent performers (in other words, managing the larger-capacity 3TB drive caused no lag in performance), we revisited the 2TB and converted its partition table to MBR. Would it be faster or slower than GPT under MBR?
We ran the same test suites, using the same Rocket 620 controller, and compared them to the GPT results for that same drive.
Whether MBR or GPT partitioning was used, the 2TB drive performed identically. In other words, using the 3TB drive under GPT will give you more capacity without slowing performance.
Note, in addition, that a Western Digital Caviar Green 3TB drive could be very useful in a dual-drive computer, with one slot filled by a solid state drive (SSD) and the other by the 3TB hard drive. The SSD could be used as a boot and application drive to increase boot-up and load times, and the hard disk drive could be used as the mass storage device.
The Western Digital Caviar Green 3TB is currently selling for around Rs. 10,400, while a 2TB Caviar Green drive can be had for about Rs. 4,400.
That's a big chunk of change for 50% more capacity. You could purchase two 2TB drives for less than the price of a single 3TB unit. However, keep in mind that you'd also end up with twice the power consumption and twice the heat generation - so it might not be a good trade-off for small form-factor computers at the very least.
In addition, if you're planning (or already have) a server farm where more than 10 of these drives are used, your power savings and heat reduction would be significant.