IO - Random and Sequential Access

Card Puncher Data Processing

About

Random access (sometimes called direct access) is the ability to access an arbitrary element of a sequence in equal time.

Random definition: can be accessed in any order

Random refers to the idea that any piece of data can be returned in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data.

The opposite is sequential access, where a remote element takes longer time to access.

Example

Device

Computer - Storage Device (Media)

Be careful as accessing media randomly as opposed to sequentially, typically yields minimum throughput.

random access device

A compact disc: You can jump right to the track you want.

sequential access device

a cassette tape, magnetic discs and optical discs

By contrast, storage devices such as magnetic discs and optical discs rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than data transfer, and the retrieval time varies based on the physical location of the next item.

With a cassette tape, you have to fast-forward through earlier songs to get to later ones. This type storage devices rely on the physical movement of the recording medium or a reading head. The movement takes longer than data transfer, and the retrieval time varies based on the physical location of the next item.

Documentation / Reference





Discover More
Data System Architecture
Collection - Sequence (Ordered)

A sequence is an abstract collection: of non-unique element where order matters - ie (A,B) is not equal to (B,A) non-unique means that it allows duplicate member (the same element/value may occur...
Data System Architecture
Concurrency - Latches (System Lock)

Latches are like semaphores. Latches are used to guarantee physical consistency of data, while locks are used to assure logical consistency of data. Latches are simple, low-level system lock (serialization...
Hierachy Storage
Disk - Characteristics

Storage technologies at all levels of the storage hierarchy can be differentiated by evaluating certain core characteristics as well as measuring characteristics specific to a particular implementation....
Harddisk
Drive - Hard (disk|drive) (HDD) - Mass Storage - Flash

A disk is a storage device that refers to magnetic media, such as: a floppy disk, the disk in your computer's hard drive, an external hard drive. It's also known as mass storage device. Disks...
Card Puncher Data Processing
I/O - IOmeter (Workload Generator)

IOmeter is a disk-testing, IO workload generator tool which generate and measure storage performance. Iometer is pronounced “eye-OM-i-ter,” to rhyme with “thermometer.”...
Card Puncher Data Processing
I/O - Workload (Access Pattern)

Each server has unique workload characteristics. However there are some basic pattern that we can found in the storage demands. Although storage system workloads differ quantitatively in terms of the:...
Data Path From Disk To Cpu
IO - Data Path / Balanced System

The data paths is the path composed of all hardware components that are needed to get the data from: a storage device (generally disk drive or network drive) to the CPU It is important to understand...
Card Puncher Data Processing
IO - IOPS (Input/Output Operations Per Second)

IOPS (Input/Output Operations Per Second, pronounced eye-ops) is a common performance measurement used to benchmark computer storage devices like: hard disk drives (HDD) solid state drives (SSD),...
Card Puncher Data Processing
IO - Throughput / Data Transfer Rate (DTR) / Bit Rate

in storage device. Throughput or data transfer rate (DTR) is : the speed at which data can be transmitted between devices. ie the rate at which information can beread from or written to the storage...
Cpu Memory System Bus
Memory - Random-access memory (RAM)

RAM (Random-access memory) known also as physical memory is a component of the the primary memory The word RAM is often associated with volatile types of memory (such as DRAM memory modules), where the...



Share this page:
Follow us:
Task Runner