HD Doctor Blog

Before discussing what a boot sector virus does, let’s first take a look at what a boot sector is. A floppy disk or hard drive is comprised of many segments and clusters of segments, which (in the case of a hard drive) may be separate by partitions. There has to be a way to find all the data spread across these segments, hence the boot sector operates as a virtual rendition of a library’s Dewey Decimal system. Each disk also has a Master Boot Record or (MBR) that locates and runs the first of any necessary operating system files needed to facilitate operation of the disk. When a disk is read, it first seeks the MBR, which then passes…

Partition Tables on MBR and GUID disks

Master boot record (MBR) disks use both basic volumes and dynamic volumes. Because partition tables on MBR disks support partition sizes only up to 2 terabytes, you must use dynamic volumes to create NTFS volumes over 2 terabytes. Windows Server 2003 manages dynamic volumes in a special database instead of in the partition table; therefore dynamic volumes are not subject to the 2-terabyte physical limit imposed by the partition table. Dynamic NTFS volumes can be as large as the maximum volume size supported by NTFS. Itanium-based computers that use GUID partition table (GPT) disks also support NTFS volumes larger than 2 terabytes.

Organization of an NTFS Volume

The figure Organization of an NTFS…

External USB, eSATA, Firewire, and internal hard drives over 2 TB’s cannot be formatted on Windows 32-bit operating systems using the Master Boot Record (MBR) partitioning scheme. As a result, when you connect drives over 2 TB’s, depending on which interface you are using to connect them to the computer, they may not be recognized at all, they may be only partially recognized, or they may be recognized but you can’t access them. Other issues such as the system locking up or the computer not being able to boot may also occur.

Cause:
This not an external or internal hard drive issue. It is a 2 TB volume limitation caused by the Master Boot Record (MBR) partitioning…

What is the MBR?

A master boot record (MBR), or partition sector, is the 512-byte boot sector that is the first sector ("LBA Sector 0") of a partitioned data storage device such as a hard disk. (The boot sector of a non-partitioned device is a Volume Boot Record. These are usually different, although it is possible to create a record that acts as both; it is called a multi boot record.) The MBR may be used for one or more of the following:

• Holding a disk’s primary partition table
• Bootstrapping operating systems, after the computer’s BIOS passes execution to machine code instructions contained within the MBR
• Uniquely identifying individual disk media, with a 32-bit

…