The OS structure

Hard disks are still the most popular form of persistent data storage. Inside a HDD is a series of round platters (disks) that spin. This is a magnetic surface which is read and written to. Most modern HDDs spin in the 7200RPM range or higher. Each platter is made up of a series of tracks,…

Page fault rate is the number of page faults occurring during a number of memory references. If the page fault was designated as f, and the memory reference was listed as t, then the page fault rate can be expressed as P = f/t, where 0 ≤ P ≤ 1. Page faults increase the time to…

Virtual Memory (VM) is a collection of one or more logical address spaces, each of which may exceed the size of physical memory. To access this space, we use a virtual address. A paged virtual memory creates a single large contiguous address space per process. Demand paging is the principle of loading a page into memory only…

If you work with a system that only has batch processes, or only does real time applications, then your scheduling algorithm selection is much easier. You pick an appropriate choice and go with it… However, the modern desktop OS will often include a combination of batch, interactive, and real-time applications. Therefore picking “a” solution isn’t…

Computer security is the freedom from theft of or damage to hardware, software, or information, and from disruption or misdirection of services. Protection is the set of mechanisms and policies that guarantee computer security, including the confidentiality, integrity, availability, and authenticity of all data and services. Common types of compromised computer security Information disclosure Information modification Information…

Errors can occur for several reasons when performing an IO operation. On a read of a disk you could have: a failed write operation the sector go bad due to age/use Additionally you could have issues with data being corrupted during transmission, especially over a long network. Therefore a parity bit is added to a series…