week8/9

Question 1

What file attributes are there

Answer 1

Name, file identifier, type, location, size, protection

Question 2

What are the two kinds of level directories

Answer 2

single level, and two level (with the top being a directory and the second being the user file directory)

Question 3

What is mounting

Answer 3

A way for directories to be accessible to the file system

Question 4

What are the 5 levels of the file system

Answer 4

Logical (permissions), file organization level (block management), basic (W/R blocks), I/O, devices

Question 5

What are the 4 On disk structures

Answer 5

boot control block (contains the code to start the OS), partition control blocks (hold the number of free blocks and the size of the blocks, called superblock), the directory structure, and the file control block (hold information about the file).

Question 6

What is the process for opening a file?

Answer 6

Search the directory for the file identifier, see if the FCB (file control…) is in the memory, allocate the entry in the process control block table (allows for the buffer to be set)

Question 7

What are three ways to allocate blocks to files

Answer 7

Contiguous (end-to-end, it’s fast), linked allocation (gives the first and last block, and points to all others in between), Indexed allocation (like linked but more overhead as one block has all the pointers)

Question 8

How do you close a file?

Answer 8

point to the FCB, decrement counter, free the process in the file control block

Question 9

Polling of I/O relies on what kind of bit?

Answer 9

the busy bit

Question 10

What is it called when devices transfer data to/from the controller

Answer 10

the direct memory access, might use physical or logical addresses

Question 11

What are examples of a character device and a block device?

Answer 11

Character= USB, keyboard
Block= disk drives, tape drives

Question 12

What is a major and minor number

Answer 12

the major number connects the device to the driver, the minor is used by the driver to work the device

Question 13

What is a distributed system? what are the two types?

Answer 13

networked processors connected by a communication protocol. Two types are Network OS, and distributed OS

Question 14

What are reasons for having distributed systems

Answer 14

Resource sharing, Reliability, Computation speedup, data migration (think NFS), process migration (like load balancing)

Question 15

What are the two types of network topology?

Answer 15

Fully connected, and partially connected

Question 16

what is a LAN and WAN?

Answer 16

Local area network, high speed, short distance.

Wide area network, long distance, private networks

Question 17

What are the 4 distributed file system concepts

Answer 17

Service (software running on machines), Server (the machine running the server software), the client and the client interface (the operations on the client that are available for use)

Question 18

What is location transparency vs independence

Answer 18

Location transparency - Name doesn’t reveal location, files are shared
Location independence - name doesn’t change if location changes. the space is shared

Question 19

What are two benefits to caching

Answer 19

Performance and consistency (more than one client can access a file)

Question 20

What are the three meanings of security

Answer 20

Protection and authentication, system integrity and information security

Question 21

what are the four security levels

Answer 21

physical, human, network, OS