Just Think and Twist

1. What is meant by Asymmetric Clustering? In this clustering, one machine is in hot standby mode, while the other is running the application. The hot standby machine just monitors the active server. If that server fails, hot standby host becomes the active server. 2. What is meant by Symmetric clustering? In this, two or more hosts are running applications and they are monitoring each other. This clustering requires more than one application be available to run and it uses all of the available hardware. 3. What is meant by parallel clusters? Parallel clusters allow multiple hosts to access the same data on the shared storage. Each machine has full access to all data in the database. 4. What is meant by symmetric multiprocessing? In Symmetric multiprocessing, each processor runs an identical copy of the operating system and these copies communicate with one another as needed. 5. What is meant by Asymmetric Multiprocessing? In Asymmetric m...

1. What is meant by Mainframe Systems? Mainframe systems are the first computers developed to tackle many commercial and scientific applications. These systems are developed from the batch systems and then multiprogramming system and finally time sharing systems. 2. What is meant by Batch Systems? In this, operators batched together jobs with similar needs and ran through the computer as a group .The operators would sort programs into batches with similar requirements and as system become available, it would run each batch. 3. What is meant by Multiprogramming? Several users simultaneously compete for system resources (i.e) the job currently waiting for I/O will yield the CPU to another job which is ready to do calculations, if another job is waiting. Thus it increases CPU utilization and system throughput. 4. What is meant by Time-sharing Systems? Time Sharing is a logical extension of multiprogramming .Here, CPU executes mu...

Vmware on LINUX VMware Workstation transforms the way technical professionals develop, test, demonstrate and deploy software by running multiple x86-based operating systems simultaneously on the same PC. VMware Workstation takes advantage of the latest hardware to replicate server, desktop and tablet environments in a virtual machine. Run applications on a breadth of operating systems including Linux, Windows® and more at the same time on the same PC without rebooting. VMware Workstation makes it really easy to evaluate new operating systems, test software applications and patches, and reference architectures in an isolated and safe environment. No other desktop virtualization software offers the performance, reliability and cutting edge features of Workstation

Setting up Xen Xen Project creates a Virtual Machine Monitor (VMM) also known as a hypervisor, this is a software system that allows the execution of multiple virtual guest operating systems simultaneously on a single physical machine. In particular, the project creates a Type 1 or “bare-metal” hypervisor, meaning that it runs directly on top of the physical machine as opposed to within an operating system. Guest virtual machines running on a Xen Project Hypervisor are known as “domains” and a special domain known as dom0 is responsible for controlling the hypervisor and starting other guest operating systems. These other guest operating systems are called Domus, this is because these domains are “unprivileged” in the sense they cannot control the hypervisor or start/stop other domains. Our hypervisor supports two primary types of virtualization: para-virtualization and hardware virtual machine (HVM) also known as “full virtualization”. Para-virtualization uses modified guest operat...

BASIC LINUX CONCEPT Linux is a multitasking, multiuser operating system, which means that many people can run many different applications on one computer at the same time. This differs from MS-DOS, where only one person can use the system at any one time. Under Linux, to identify yourself to the system, you must log in, which entails entering your login name (the name the system uses to identify you), and entering your password, which is your personal key for logging in to your account. Because only you know your password, no one else can log in to the system under your user name Administration Requirements On traditional UNIX systems, the system administrator assigns you a username and an initial password when you are given an account on the system. However, because in Linux tt you are the system administrator, you must set up your own account before you can log in In addition, each system has a hostname assigned to it. It is this hostname that gives your machine a name, gives ...

1.File Structure · All disk I/O is performed in units of one block (physical record) size which will exactly match the length of the desired logical record. · Logical records may even vary in length. Packing a number of logical records into physical blocks is a common solution to this problem. · For example, the UNIX operating system defines all files to be simply a stream of bytes. Each byte is individually addressable by its offset from the beginning (or end) of the file. In this case, the logical records are 1 byte. The file system automatically packs and unpacks bytes into physical disk blocks – say, 512 bytes per block – as necessary. · The logical record size, physical block size, and packing technique determine how many logical records are in each physical block. The packing can be done either by the user’s application program or by the operating system. 2.Directory Structure There are five directory structures. They are 1. Single-level directory ...

Contiguous Allocation Each process is contained in a single contiguous section of memory. · There are two methods namely : · Fixed – Partition Method · Variable – Partition Method · Fixed – Partition Method : o Divide memory into fixed size partitions, where each partition has exactly one process. o The drawback is memory space unused within a partition is wasted.(eg.when process size < partition size) · Variable-partition method: o Divide memory into variable size partitions, depending upon the size of the incoming process. o When a process terminates, the partition becomes available for another process. o As processes complete 2.Segmentation o Memory-management scheme that supports user view of memory o A program is a collection of segments. A segment is a logical unit such as Main program, Procedure, Function, Method, Object, Local variables, global variables, Common block, Stack, Symbol table, arrays 3.Demand Paging It...

· In Virtual machine environment, there is the complete protection of the various system resources. · Each virtual machine is completely isolated from all other virtual machines, so we have no security problems as the various system resources are completely protected. · No direct sharing of resources. · Sharing in two ways i. Share a   mini disk   (files can be shared) ii. Define a network of virtual machines, each of which can send information over the virtual communication network. The · Virtual machine is a perfect vehicle for OS research and development. · The OS runs on and controls the entire machine. Thus it is necessary to test all changes to the operating system carefully. This period is System Development time since it makes the system unavailable to users, which is eliminated by virtual machine system. System programs are given their own virtual machine and system development is done on the virtual machine, instead of a physical machi...

The OS provides certain services to programs and to the users of those programs. 1. Program execution: The system must be able to load a program   into memory   and to run that program. The program must be able to end its execution, either normally or abnormally (indicating an error). 2. I/O operations: A running program may require I/O. This I/O may   involve a   file or an I/O device. 3. File-system manipulation: The program needs to read, write, create,   delete files. 4. Communications : In many circumstances, one process needs to   exchange information   with another process. Such communication can occur in two major ways. The first takes place between processes that are executing on the same computer; the second takes place between processes that are executing on different computer systems that are tied together by a computer network. 5. Error detection: The operating system constantly needs to be aware   of possible...

Operating System Components There are eight major operating system components.They are · Process management  · I/O-system management  · Secondary storage management  · Networking  · Protection system   · Command-interpreter system  (i) Process Management · A  process  can be thought of as a program in execution. A batch job is a process. A time-shared user program is a process.  · A process needs certain resources including CPU time, memory, files, and I/O devices to accomplish its task.  · A program by itself is not a process; a program is a  passive  entity, such as the contents of a file stored on disk, whereas a process is an  active  entity, with a  program counter  specifying the next instruction to execute.  · A process is the unit of work in a system.  · The operating system is responsible for the following activities in connection wit...