What are the different types of booting?

Answer 1

They are of two types:

• Single-Boot is the act of installing only one operating system on a computer and it being able to boot automatically when the computer starts.
• Multi-Boot is the act of installing multiple operating systems on a computer, and being able to choose which one to boot when the computer starts.

In addition, there are several type of booting divided by the source (i.e. location) of the boot code:

• Non-volatile storage boot - by far the most common, the boot code resides in some sort of fixed storage media internal to the machine. EEPROMs and hard disks are by far the most common source for fixed storage, though NVRAM (non-volatile RAM) in the form of NAND (flash) memory is becoming increasingly popular. However, it can apply to any fixed-media device, including tape drives, punch cards, and other antiquated devices.
• Network boot - common in many server systems and with larger-scale deployments of managed node systems, the system obtains the necessary boot code instructions as a reply to a request broadcast via its network connection. That is, to boot, the computer sends out a request for boot instructions via its network card, and waits for a reply (with the relevant boot information) from a specially-configured server attached to the same network.
• Manual boot - a relic of the start of the computer industry. Certain ancient computers required a human to manually toggle in boot instructions (in binary) via a series of switches on the front of the computer. This method of booting was obsoleted as soon as the first practical permanent storage systems was developed, and will only be seen on computers from the 1940s and very, very early 1950s.

Finally, there are two different methods by which a boot can be initiated:

A "Hard Boot" (also known as a "Cold Boot") consists of power cycling the entire system; that is, terminating power to every component, the powering up again from scratch. This is most commonly associated with a manyal step, typically by pushing a power cycle button (often just call the Power Button, and typically a large red button). Hard booting forces all components to completely de-power and clears all the state of the entire system. In more advanced machines, a Hard Boot can take up to several hours, as it usually involves significant self-diagnosis tests run by each component.

A "Soft Boot" (also known as "Warm Boot") consists of exiting the currently running OS, and returning control to the hardware supervisor (on a PC, the BIOS), which then re-initiates the OS boot, without forcing hardware components to clear state or de-power. By skipping all the hardware self-diagnosis and state clearing, significant time can be saved. Soft Boots are usually initiated by the Operating System itself - for example, on many modern PCs with Windows 7, the "reboot" option presented in the Windows Menu is really a "Soft Reboot". Certain hardware (for instance, Macs and many UNIX workstations) will have the physical red Power Button initiated a OS Soft Reboot, rather than a Hardware Hard Boot, if they are pressed. These systems will initiate a Hard Boot if the Power Button is held down for several seconds.

Also, note that "booting" is not a single event. It really is called "bootstrapping", and refers to a long series of events, where a chain of programs load sequentially. The boot process begins with a very, very, very simple program that resides in the BIOS (or equivalent) code on the mainboard, which is justsmart enough to load itself, then hand execution to another program in some specific location. A similar chain of events happens in the next program and the next, until something finally is smart enough to start the operating system kernel itself.

The above answers and references to the kernel are from Linux/UNIX users (I am one myself), but there is also "Safe Mode" in the MS Windows Operating System which loads without many of the drivers assuming that the failure of your last boot is due to a driver issue.

Actually, nothing in the first two answers is specific to ANY operating system. ALL operating systems have a kernel, and the process of booting is the same on all modern hardware, from microprocessor-run OSes ones like Windows, Linux and UNIX, to minicomputer-based VMS, to mainframe z/OS, to even hypervisors like VMWare, Xen, or z/VM.

"Booting" is simply the process for bringing a computing system "alive" - that is, from a non-running state (usually, powered off) to the point where an Operating System now has control.

Answer 2

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