Computer Systems Definitions Quiz

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Questions and Answers

What does the Domain Name System (DNS) provide?

Host-name-to-network address translations

What is the purpose of the Common Internet File System (CIFS)?

To create network logins using user authentication.

What are the two techniques used to optimize sequential access?

Free-behind and read-ahead.

What is the purpose of the File-open count?

To allow removal of data from the open-file table when the last process closes the file. Signup and view all the answers

What is the main purpose of the buffer cache?

To store frequently used blocks of data from main memory. Signup and view all the answers

What does the 'write ahead' part of journaling mean?

Writing notes on the disk to describe what you're doing before overwriting on-disk structures. Signup and view all the answers

What is the difference between Global replacement and Local replacement in memory management?

Global replacement allows a process to take a replacement frame from another process's set of allocated frames, while Local replacement only allows a process to take a frame from its own set of allocated frames. Signup and view all the answers

The 'virtual address space' is the physical location of where a process is stored in memory.

False Signup and view all the answers

What does the 'Copy-on-Write' strategy allow?

Both parent and child processes to initially share the same pages in memory. Signup and view all the answers

What are the four necessary conditions for a deadlock?

Mutual exclusion, no preemption, hold and wait, and circular wait. Signup and view all the answers

What is the purpose of the 'Lazy swapper' in memory management?

Never swap a page into memory unless that page is actually needed. Signup and view all the answers

What are the three file operations used for writing data to a file?

Create, Write and Delete. Signup and view all the answers

What is the purpose of the 'page address extension' (PAE)?

To allow 32-bit applications to access more than 4GB of memory space. Signup and view all the answers

What are the three file operations used when reading data from a file?

Read, Reposition within file and Delete. Signup and view all the answers

What is the difference between the 'Shared lock' and 'Exclusive lock'?

A shared lock allows multiple processes to read a file concurrently, while an exclusive lock prevents all other processes from accessing a file, including reading, until the lock is released. Signup and view all the answers

What does the term 'File Session' denote?

Series of accesses between file open and closed. Signup and view all the answers

What does the term 'Positioning time' refer to?

The time taken to move the disk arm to the desired cylinder and then wait for the desired sector to rotate under the disk head. Signup and view all the answers

How do 'Striped mirrors' (RAID 1+0) or 'mirrored stripes' (RAID 0+1) improve performance and reliability?

They provide high performance and reliability by combining the benefits of mirroring and striping. Signup and view all the answers

What is the purpose of the system call 'ioctl'?

It manipulates the device parameters of files and changes physical to virtual address. Signup and view all the answers

What does 'Virtual File System' (VFS) layer do?

Distinguishes local files from remote ones. Signup and view all the answers

What is the difference between the 'Most Frequently Used' (MFU) algorithm and the 'Least Frequently Used' (LFU) algorithm?

The Least Frequently Used (LFU) algorithm replaces the page with the smallest count, while the Most Frequently Used (MFU) algorithm replaces the page with the largest count. Signup and view all the answers

What is the primary purpose of the 'Mount table'?

To store file system mounts, mount points, and filesystem types. Signup and view all the answers

Study Notes

Definitions and Terms

Deadlock Detection: A method to identify deadlocks in a computer system.
Client-Server Model: A computing model where one system (client) requests services from another system (server).
Journaling File Systems: Systems that log actions to a journal before they are executed on disk. This provides data integrity and recovery capabilities.
NFS (Network File System): A protocol and implementation for allowing access to remote files over a network.
VFS (Virtual File System): A layer that distinguishes local and remote files. It hides the underlying differences between file systems.
Journaling: A system for logging changes to file/data systems, enabling recovery in case of failures.
Journal Write: Record the transaction in a log file.
Journal Commit: Write the transaction commit block to disk
Checkpoint: Write the contents of updates to their locations.
FCB (File Control Block): A structure containing information about a file, including its location, size, and permissions.
Root Partition: Contains the operating system (OS).
DNS (Domain Name System): Translates hostnames to network addresses.
NIS (Network Information Service): Provides user authentication for network logins.
CIFS (Common Internet File System): A protocol used for network file sharing.
File Session: A series of access operations to a file.
RAID (Redundant Array of Inexpensive Disks): A technology that uses multiple disks to improve data reliability and performance.

Additional Concepts

Demand Paging: A memory management technique where pages are loaded into memory only when they are needed.
Banker's Algorithm: An algorithm for resource allocation that prevents deadlocks by considering the needs of all processes.
Deadlock Conditions: Mutual Exclusion, Hold and Wait, No Preemption, Circular Wait
File Attributes: Includes the file's name, identifier, type, location, size, protection and date-time.
File Operations: Create, write, read, reposition, delete, truncate, open, close.
Buffer Cache: A memory area for frequently used blocks.
Page Cache: Caches pages in memory to speed up access.
Virtual Memory: A memory management technique that uses disk space as an extension of RAM.
Lazy Swapper: A memory management technique that defers loading pages into memory until they're needed.
Copy-on-Write (COW): Allows sharing of the same file by parent and child processes.
Least Frequently Used (LFU) Algorithm: A method for replacing pages in memory based on their frequency of use.
Most Frequently Used (MFU) Algorithm: An algorithm for replacing pages in memory based on their usage frequency.
Global Replacement: Replacing a frame from any available frame.
Local Replacement: Replacing a frame only from the allocated resource for that process.
Page Address Extension (PAE): Extends the addressable memory space to accommodate more memory per each application.
Resource Type, Allocation, Request, and Available: Management of resources of each type for multiple processes.

System-Level Concepts

Device Drivers: Manage I/O devices.
Mount Table: Stores information about file system mounts; type of file system, and location of the corresponding file system.
System-Wide Open-File Table: Contains a copy of the FCB for each open file.
Per-Process Open-File Table: Contains pointers to appropriate entries in the system-wide open-file table.
Collisions: A condition where multiple file names hash to the same location.
Free-Behind and Read-Ahead: Techniques to optimize sequential file access.
Transfer Rate: Data transfer rate between computer and drive.
Positioning Time: Time taken to move the head to a specific location in a disk to execute a read/write operation, including seek time and rotational latency.
Head Crash: Mechanical disk failure when the disk head touches the surface of a disk, causing damage.
Access Latency: Total access time for an I/O operation, calculated as the sum of average seek time, and latency.
RAM Drives Devices that appear as raw blocks of memory.
Error Correction Code (ECC): Detects and corrects errors in data transfers.
Mean Time to Repair (MTTR): Average time to repair a system failure.
Mean Time to Data Loss (MTTDL): Average time before data loss occurs, due to equipment failures, etc.

Tutorials/Study Assignments

FIFO: First-In, First-Out scheduling, often used in data queues and processes.
Rendezvous: A mechanism to synchronize processes, often used in shared memory.
Futex: Fast Userspace Mutex, a user-space synchronization primitive.
Ioctl: System call to manipulate device parameters.
Sync, Echo, and Buffer: Mechanisms used for data synchronization, communication, and buffering.
Memory Allocation Schemes with internal fragmentation: Fixed Partitioning and Paging
LRU, Second Chance, FIFO, and RECENCY BIT: Page Replacement algorithms for virtual memory.
CPU Utilization: Refers to the percentage of CPU time being utilized by a task or a collection of processes.
Decrease in Multiprogramming: A way to improve computer system efficiency.
Disk Scheduling: Scheduling the order in which disk requests are served.
Turnaround Time: The whole time taken for a process to complete execution.
Major and Minor Numbers Numbers used to distinguish between different devices.
Mandatory vs Discretionary Access Control: Different approaches to file access protection.

Other important Terms

File-open count: Number of times a file is opened.
Shared Lock: Similar to read-lock.
Exclusive Lock: Similar to write-lock.

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Description

Test your knowledge on key definitions and terms related to computer systems. This quiz covers essential concepts such as deadlock detection, client-server models, and journaling file systems. Develop a deeper understanding of how file systems operate and the protocols involved.