After pushing the capacity boundaries of external HDDs, Seagate has brought a three-terabyte internal drive to the desktop PC with the Barracuda XT 3TB. With 3TB being the largest capacity offered by Western Digital, Seagate and Hitachi, you now get 50 per cent more space than the previous giants (2TB).

What sets Seagate's Barracuda XT 3TB drive apart, how does it perform and should storage aficionados get this drive with so much storage capacity?

Design and specifications

This drive features increased areal density, leading to 600GB per platter. To achieve 3TB, then, it uses five platters and ten heads. Aside from this, it is mostly a continuation of what Seagate's Barracuda XT 2TB started.

The 3TB drive looks the same, following Seagate's standard design and colour scheme. It is a standard desktop HDD, with a 3.5in form factor and SATA 6Gbps interface. It spins at 7,200rpm and has a 64MB buffer.

Power usage claimed is 7.37W at idle and 9.23W during operation. While in use under normal conditions, it was barely audible, just like any HDD. While testing and in heavy usage though, the drive was slightly more audible. Heat of course, was in plentiful supply considering it's large number of platters. Make sure to give this drive a lot of ventilation and airflow.

The Seagate Barracuda XT 3TB (ST33000651AS) provides 2794.52 GB of usable space, after formatting. Seagate offers a five year warranty on this product. More details can be seen on Seagate's product page for the drive.

Software bundle

Windows cannot recognise more than 2048GB of a drive in the legacy MBR mode (known as the 2.2TB ceiling problem).

Seagate provides a workaround to this problem in its most recent version of Seagate DiscWizard (a download of 152.8MB). DiscWizard enables access to the full 3TB capacity even while using this drive in MBR mode. A requirement is the latest driver for Intel Storage controller, on motherboards with Intel chipsets.

Seagate Barracuda XT 3TB

Unlike some brands, Seagate's use of this software means you are not forced to use a hardware solution (HBA) to get over the 2.2TB ceiling. DiscWizard is significant because it allows users to boot from this 3TB drive and use its full capacity, breaking OS limitations (WinXP is limited to 2.1TB) and making UEFI BIOS unnecessary to use a large capacity HDD.

However, note that most motherboards made in the past couple of years do support drives larger than 2.2TB, just as long as the drive is initialised as a "GPT" drive instead of MBR. But in such a case, you must boot from a different drive if your motherboard does not have a UEFI BIOS with support for booting from a GPT drive.


Our colleagues at PC World India put the Seagate Barracuda XT 3TB through its paces in their labs. Here's how the hard drive held up to testing.

We run synthetic benchmarks and real world tests using the fastest PC components at hand, to remove most bottlenecks that hold back performance. The testbed consisted of an Intel Core i7 965 processor, Intel DX58SO motherboard, AMD Radeon 5970 graphics card, Intel X25-M 80GB SSD, WD VelociRaptor 300GB, 12GB of Silicon Power DDR3 RAM in triple channel, Tagan BZ-1300W PSU and Windows 7 Ultimate SP1 64bit edition. We used the latest WHQL signed drivers available at the time of testing.

A RAMdisk drive was used for real world file transfer tests, and a SATA III adaptor to operate this drive at full capability. To prevent any chance of the software layer interfering with speeds, we initialised and tested the drive in GPT mode to get pure numbers.

Seagate Barracuda XT 3TB

We measured a read speed average of 134.2MBps (megabytes per second), and write speed average of 121.9MBps. Real world file read/write speeds stood at 107MBps for a single large file (6.42 GB), but fell to 83MBps as expected, when copying multiple smaller files (1287 files totalling up to 2.33 GB).

Transferring files from the first partition to a second on the same drive was at a speed of 43MBps. Read and write access times averaged 16.7ms and 7.56ms respectively. The drive racked up a HDD Score of 8472 in PC Mark 05.

The Barracuda XT's 7,200rpm means a higher spinning rate than the Barracuda LP 5,900rpm drives. Performance turned out to be accordingly higher. These performance numbers are good but are not all that much higher than mainstream desktop hard drives priced far lower than the XT 3TB. So it would seem that SATA 6Gbps sported by this drive still is only hype and actual speeds don't even saturate what the older SATA 3Gbps offers.


The Seagate Barracuda XT 3TB is a nice advance, with more data density and slightly better performance. More evolutionary than revolutionary, the fact that magnetic hard disk drives are still moving forward is the prime takeaway from this product. It is understandably not aimed at the mainstream, so the higher price for now is not cause for concern. If you want a performance drive and need the storage space anyway, buy it.