Visit for more Learning Resources Terms of HDD Sides or head Track Sectors Cylinder Sector Interleaving Landing zone MBR master boot record Zone recording Write Precompensation Visit for more Learning Resources

Storing the Data The process of low-level formatting a drive establishes the tracks and sectors on the platter. The starting and ending points of each sector are written onto the platter. This process prepares the drive to hold blocks of bytes. High-level formatting then writes the file- storage structures, like the file-allocation table, into the sectors. This process prepares the drive to hold files. 2

Tracks, Cylinders, and Sectors The tracks are numbered, starting from zero, starting at the outside of the platter and increasing as you go in. A modern hard disk has tens of thousands of tracks on each platter. Data is accessed by moving the heads from the inner to the outer part of the disk, driven by the head actuator. This organization of data allows for easy access to any part of the disk, which is why disks are called random access storage devices. 3

Tracks, Cylinders, and Sectors The tracks are numbered, starting from zero, starting at the outside of the platter and increasing as you go in. A modern hard disk has tens of thousands of tracks on each platter. Data is accessed by moving the heads from the inner to the outer part of the disk, driven by the head actuator. This organization of data allows for easy access to any part of the disk, which is why disks are called random access storage devices. IT: Computer Maintenance - Hard Drives 4

The Difference Between Tracks and Cylinders A hard disk is usually made up of multiple platters, each of which uses two heads to record and read data: one for the top of the platter and one for the bottom. The heads that access the platters are locked together on an assembly of head arms. This means that all the heads move in and out together, so each head is always physically located at the same track number. It is not possible to have one head at track 0 and another at track 1,000. IT: Computer Maintenance - Hard Drives 5

The Difference Between Tracks and Cylinders A hard disk is usually made up of multiple platters, each of which uses two heads to record and read data: one for the top of the platter and one for the bottom. The heads that access the platters are locked together on an assembly of head arms. This means that all the heads move in and out together, so each head is always physically located at the same track number. It is not possible to have one head at track 0 and another at track 1,000. IT: Computer Maintenance - Hard Drives 6

The Difference Between Tracks and Cylinders A hard disk is usually made up of multiple platters, each of which uses two heads to record and read data: one for the top of the platter and one for the bottom. The heads that access the platters are locked together on an assembly of head arms. This means that all the heads move in and out together, so each head is always physically located at the same track number. It is not possible to have one head at track 0 and another at track 1,000. Copyright © Texas Education Agency, 2011. All rights reserved. IT: Computer Maintenance - Hard Drives 7

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. 8

Interleaving However, the physical sectors on a track are adjacent to each other and not separated by very much space. Reading sectors consecutively requires a certain amount of speed from the hard disk controller. The platters never stop spinning, and as soon as the controller is done reading all of sector #1, it has little time before the start of sector #2 is under the head. Many older controllers used with early hard disks did not have sufficient processing capacity to be able to do this. They would not be ready to read the second sector of the track until after the start of the second physical sector had already spun past the head, at which point it would be too late. IT: Computer Maintenance - Hard Drives 9

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. IT: Computer Maintenance - Hard Drives 10

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. IT: Computer Maintenance - Hard Drives 11

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. IT: Computer Maintenance - Hard Drives 12

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. 13

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. 14

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. IT: Computer Maintenance - Hard Drives 15

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. IT: Computer Maintenance - Hard Drives 16

Interleaving A common operation when working with a hard disk is reading or writing a number of sectors of information in sequence. After all, a sector only contains 512 bytes of user data, and most files are much larger than that. Let's assume that the sectors on each track are numbered consecutively, and say that we want to read the first 10 sectors of a given track on the hard disk. Under ideal conditions, the controller would read the first sector, then immediately read the second, and so on, until all 10 sectors had been read. Just like reading the first 10 words in this sentence in a row. IT: Computer Maintenance - Hard Drives 17

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