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Partition Table

Partition table is big table data into called the many small subset division. If hard disk lost partition table, data cannot read and write in sequence, can't operate.


The traditional partition scheme (called MBR partition scheme) is to partition information saved to disk first sector (MBR sector) of 64 bytes, each partition of take up 16 bytes, this 16 bytes are the activity, the file system identification marks, start-stop cylinder number, head number, number, implied sector sector number (4 bytes), the total number of partition sector (4 bytes), etc. Due to the MBR sector only 64 bytes for partition table, so can only record four division of the information. This is the hard disk partition number no more than four reasons. Later in order to support more division, the introduction of the extended zoning and logic zoning concepts. But each partition still using the 16 bytes of storage.

MBR partition scheme not with well? Why to want to put forward the new plan? Let's see what the problems are scheme MBR division. Had mentioned in front the number can't more than four division of limit, this is one, most of the time, the four primary partition and can't meet the need. In addition the key division scheme can't support more than MBR 2 TB capacity of the disk. Because the plan with four bytes of storage area total number of sectors, the maximum of 2 can say the number 32 power sector, according to each sector 512 bytes, each partition biggest no more than 2 TB. After more than 2 TB disk capacities, the division of the starting position cannot be said. The hard drive capacity by leaps and bounds today, 2 TB restrictions will soon be breakthrough. This shows, MBR partition plan has been unable to meet the need.


A based on the computer by Itanium can be expanded the firmware interface (EFI) use disk partition architecture. And the Lord start record (MBR) than partition method, has more advantages GPT, because it allows each disk as many as 128 partition, support up to 18 billion bytes of the volume of size, allowing the disk partition table and backup disk partition table used for redundancy, also support the only disk and partition ID (GUID). And support for maximum volume 2 TB (terabytes) and each disk at most four main division (or 3 main division, a division and unlimited expansion of logical drive) Lord start record (MBR) disk partition compared the style, GUID partition table (GPT) disk partition style support for maximum volume 18 EB (exabytes) and each disk at most a 128 division. And the MBR division of the disk is different, very important platform in operation data partition, not in the division or hidden sector. In addition, GPT division have a surplus of main and disk backups partition table to improve partition the integrity of the data structure.

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