What & How & Why

For SATA, USB, SAS, these type of devices are showing in Linux like:

/dev/sd[a-]

the a after sd indicates the currently number of harddisk. The order of these number is only associate with the computer checking sequence for harddrives. First is a , then b… For older IDE, the old version of Linux call them:

/dev/hd[a-]

Since IDE harddrives is no longer used in new generation computers, some new version Linux just put them into sd aslo.

For more devices name: Link

MBR: Master boot record
A master boot record (MBR) is a special type of boot sector at the very beginning of partitioned computer mass storage devices like fixed disks or removable drives intended for use with IBM PC-compatible systems and beyond. The concept of MBRs was publicly introduced in 1983 with PC DOS 2.0.
MBR infos are usually stored at the first sector of hardrive. It take space of one sector(usually 512Bytes). In this space, there are two mainly data are stored in it:

• MBR (446Bytes in classic MBR)
• Partition Table(64 Bytes, Divided into 4 parts)

So partition in Liunx usually is shown like:

/dev/sd[hardrive number][partition number]

A primary partition contains one file system. In DOS and all early versions of Microsoft Windows systems, Microsoft required what it called the system partition to be the first partition.

Partition is used for keeping data safe by separating sectors into different range. Because Partition table only supports 4 partitions, for getting more partitions, people use a record called extended boot record (EBR) to create a new partition that we called Extended partition.In Extended Partition, the space could be divided into 4 or more pieces. Each pieces is called Logical partition.

In MBR, the frist 4 numbers are reserved by primary partition and extended partition. Thus, the devices for partition should be like this:

/dev/sda[1-4] // primary partition and extended partition
/dev/sda[5-]  // logical partition