OS202
Since main memory is usually too small to accommodate all the data and programs permanently, the computer system must provide secondary storage to back up main memory. Modern computer systems use disks as the primary on-line storage medium for information (both programs and data). The file system provides the mechanism for on-line storage of and access to both data and programs residing on the disks. A file is a collection of related information defined by its creator. The files are mapped by the operating system onto physical devices. Files are normally f organized into directories for ease of use.
A storage array, also called a disk array, is a data storage system for block-based storage, file-based storage, or object storage. Rather than store data on a server, storage arrays use multiple drives in a collection capable of storing a huge amount of data, managed by a central management system. The performance of storage arrays can be improved by using a high-quality management system to keep track of capacity, errors, and trends. In this guide, I discuss the basics of storage arrays, including what they are, how they work, common setups of data centers, and how monitoring tools can help improve array performance. I also review the key features of several of these top solutions, and explain why Storage Resource Monitor is my best pick for 2020 due to its unified management system, performance optimization capabilities, and storage capacity forecasting features.
RAID (Redundant Arrays of Independent Disks)
RAID, or “Redundant Arrays of Independent Disks” is a technique which makes use of a combination of multiple disks instead of using a single disk for increased performance, data redundancy or both. The term was coined by David Patterson, Garth A. Gibson, and Randy Katz at the University of California, Berkeley in 1987. Data redundancy, although taking up extra space, adds to disk reliability. This means, in case of disk failure, if the same data is also backed up onto another disk, we can retrieve the data and go on with the operation. On the other hand, if the data is spread across just multiple disks without the RAID technique, the loss of a single disk can affect the entire data.
BIOS (basic input/output system)
BIOS (basic input/output system) is the program a computer’s microprocessor uses to start the computer system after it is powered on. It also manages data flow between the computer’s operating system (OS) and attached devices, such as the hard disk, video adapter, keyboard, mouse and printer. The main use of BIOS is to act as a middleman between OSes and the hardware they run on. BIOS is theoretically always the intermediary between the microprocessor and I/O device control information and data flow. Although, in some cases, BIOS can arrange for data to flow directly to memory from devices, such as video cards, that require faster data flow to be effective.
Unified Extensible Firmware Interface (UEFI)
UEFI stands for Unified Extensible Firmware Interface. This special interface is a kind of miniature operating system which starts up immediately after booting the computer’s motherboard (also referred to as the mainboard) and its corresponding hardware components. It ensures that a special start-up program (referred to as a bootloader) can be loaded in the memory and then execute additional operational routines. Usually, this process ends with the login screen. The user then enters the required information (user name and password) at which point the computer can be used for specific tasks (e.g. word processing, etc.).
Advanced Configuration and Power Interface (ACPI)
ACPI, or Advanced Configuration and Power Interface, is an open industry specification that enables software designers to integrate features for power management throughout a computer system, including the hardware, operating system, and application software. Advanced Configuration and Power Interface (ACPI) is supported by the Microsoft Windows family and enables the operating system to handle all the power-management resources for computer subsystems and peripherals. ACPI works with subsystems and peripherals for a wide range of mobile, desktop, and server platforms. ACPI is also the foundation for the OnNow industry initiative that enables computers to start at the touch of the keyboard.
Windows Boot Manager (BOOTMGR)
Windows Boot Manager (BOOTMGR), a small piece of software, is loaded from the volume boot code that is a part of the volume boot record. It enables you to boot Windows 10/8/7 or Windows Vista operating system. Besides, MiniTool will offer more information to you. The configuration data that BOOTMGR requires can be found in the Boot Configuration Data (BCD) store, which is a registry-like database. The database replaces the boot.ini file used in old Windows versions like Windows XP. The BOOTMGR file itself is both read-only and hidden, which is located in the root directory of the partition. It is marked as “Active” in Disk Management. In most Windows PCs, this partition is labelled as “System Reserved” without hard drive letter. If there’s no the “System Reserved” partition, probably the BOOTMGR is located on the primary hard drive (in most cases it’s C drive). The boot manager will execute winload.exe, which is the system loader that is used to continue the Windows boot process.
LILO stands for Linux Loader that is used to load Linux into memory. It can boot operating systems from floppy disks, hard disks, and it does not depend on a specific file system. Lilo handles some tasks such as locate the kernel, identify other supporting programs, load memory and starts the kernel. The configuration file of lilo is located at “/etc/lilo.conf”. Lilo reads this configuration file and it tells Lilo where it should place the bootloader.
GRUB (Grand Unified Bootloader)
The GRUB (Grand Unified Bootloader) is a bootloader available from the GNU project. A bootloader is very important as it is impossible to start an operating system without it. It is the first program which starts when the program is switched on. The bootloader transfers the control to the operating system kernel.
Operating System Initialization
The initialization process prepares the hardware for an operating system to take control. An operating system organizes the system resources: the peripherals, memory, and processing time. With an operating system controlling these resources, they can be efficiently used by different applications running within the operating system environment. ARM processors support over 50 operating systems. We can divide operating systems into two main categories: real-time operating systems (RTOSs) and platform operating systems.