Understanding Secondary Storage of Operating system
-By Arbaj Khan (Data science student)
Introduction:
Secondary storage is the nonvolatile repository for (both user and system) data and programs. As (integral or separate) part of an operating system, the file system manages this information on secondary storage. Uses of secondary storage include storing various forms of programs (source, object, executable) and temporary storage of virtual memory pages (paging device or swap space). Information in secondary storage may be in a variety of forms, including readable text and raw data (e.g., binary).
History:
- 1928 Magnetic Tape : Fritz Pfleumer, a German engineer, patented magnetic tape in 1928. He based his invention off Vlademar Poulsen’s magnetic wire.
- 1930 Magnetic drum : G.Taushek, an Austria innovator, invented the magnetic drum in 1932. He based his invention off a discovery credited to Fritz Pfleumer
- 1946 Williams Tube : Professor Fredrick C. Williams and his colleagues developed the first random access computer memory at the University of Manchester located in the United Kingdom. He used a series of electrostatic cathode-ray tubes for digital storage. A storage of 1024 bits of information was successfully implemented in 1948
- 1956 Hard Disk : A hard disk implements rotating platters, which stores and retrieves bits of digital information from a flat magnetic surface.
- 1966 DRAM (PDF) : In 1966, Robert H. Dennard invented DRAM cells. Dynamic Random Access Memory technology (DRAM), or memory cells that contained one transistor. DRAM cells store bits of information as an electrical charge in a circuit. DRAM cells increased overall memory density
- 1970 Bubble Memory : In 1970, Andrew Bobeck invented the Bubble Memory, a thin magnetic film used to store one bit of data in small magnetized areas that look like bubbles. The development of the Twister memory enabled him to create Bubble Memory.
- 1984 CD Rom : The CD-ROM, also known as the Compact Disk Read-Only Memory, used the same physical format as the audio compact disks to store digital data. The CD-ROM encodes tiny pits of digital data into the lower surface of the plastic disc, which allowed for larger amounts of data to be stored.
- 1990 Zip : The Zip drive became commonly used in 1994 to store digital files. It was a removable disk storage system introduced by Iomega.
- 2003 Blu Ray (PDF) : Blu-Ray is the next generation of optical disc format used to store high definition video (HD) and high density storage. Blu-Ray received its name for the blue laser that allows it to store more data than a standard DVD. Its competitor is HD-DVD
- Today Cloud Backup Solutions : Zetta’s cloud enables businesses to protect data using backup, recover from a disaster, and archive unused files using only a lightweight sofware client and Zetta’s bi-coastal datacenters. As storage hardware and internet bandwidth continue to develop, so will Zetta’s performance
The Function of Secondary Storage :
The function of secondary storage is the long-term retention of data in a computer system. Unlike primary storage, or what we refer to as memory, secondary storage is non-volatile and not cleared when the computer is powered off and back on. Secondary storage is cheaper than primary storage but is also slower in both read and write access. Primary storage is faster but doesn’t store data persistently, instead loading data from the slower secondary storage into primary in order to make efficient use of it. Unlike primary storage, secondary storage also doesn’t directly access the computer’s CPU.
Magnetic drives, or hard drives, are the most common form of secondary storage. All modern computers typically use at least one internal hard drive, and many come equipped with more. Hard drives are also frequently attached externally through a Universal Serial Bus (USB) or Firewire, and they are also used in arrays for redundant and recoverable storage in case of accidental data loss.
Disk drives were the former kings of secondary storage, but for the most part they have fallen by the wayside. Disk drives operate similarly to hard drives but use a much less dense material to store data. Initially, disk drives were the cheapest way to store data, but eventually the price per unit of storage on hard drives superseded the capacity and price of disk drives. A 3.5-inch disk could hold, at most, 1.44Mb of data, or about one millionth of the data of today’s typical hard drive.
Flash memory has enjoyed a boom in popularity and technological advances. It functions much like a hard disk in term of access, albeit faster due to the storage medium not being sequentially written like a hard disk platter. Flash memory can be thought of as slower, non-volatile memory, but it is still unable to directly access a computer’s CPU. As its capacity has increased while its prices have fallen, flash memory has become a direct competitor of hard disks: it has faster read and write times and better mechanical stability, as it has no moving parts.
Secondary Storage Management :
As mentioned, the OS is responsible for secondary storage. Usually comprising many hard-disk drives, but possibly also some solid-state NVRAM, secondary storage delivers high density and non volatility for long-term storage. The OS may manage access to local disks for each node or a separate part of the system of disks connected by a storage area network such as a redundant array of independent disks configuration (there are several) for higher access bandwidth and greater reliability through redundancy of storage. While secondary storage is important to users in its OS support for file systems, it also provides other services.
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