CSC 415 Operating System Principles Unit 06 Part 2
Using ____-bit pointers limits the size of a file to 4 GB. Select one: a. 64 b. 128 c. 256 d. 32
d. 32
What is the single best method of recovery Select one: a. Error correction code b. Checksums c. Journaling d. Backup
d. Backup
What is the size of the bit vector of a 1TB disk with 512-byte blocks? Select one: a. 8 MB b. 268 MB c. 2 MB d. 28 MB
b. 268 MB
_______________ is used to implement a file system. Select one: a. A volume control block b. A directory structure. c. all of the other answers d. A boot control block
c. all of the other answers
The information about a file as owner, group, rights etc. are stored Select one: a. globally, in in-memory structure maintained by the operating system b. globally, in the global on-disk structure for each file system c. globally, in the global on-disk structure stored maintained by the operating system d. locally, with other file attributes
d. locally, with other file attributes
Each system should have at least one file system which is bootable. Select one: a. False b. True
b. True
In file systems consistent with Session Semantics, the changes in a file are made visible to new sessions only, but are not seen by current sessions. Select one: a. False b. True
b. True
All remote file systems allow clients to mount only one file system from remote machines. Select one: True False
False
Any user can always read any file. Select one: True False
False
Double-caching improves the memory usage efficiency and prevents file corruption Select one: True False
False
If Free = 1; The following bit vector represents a disk where blocks 1, 5, 8, 11, 14 are free and the rest allocated - 1011101101101101.... Select one: True False
False
NFS (Network File System): Select one: a. is not fully consistent with UNIX Semantics. b. is consistent with Session Semantics. c. is consistent with Immutable-Shared-Files Semantics. d. is consistent with UNIX Semantics.
a. is not fully consistent with UNIX Semantics.
The file owner: Select one: a. is the user who can change the file attributes and grant access to the file. b. is the only user who can execute the file. c. is the user who cannot change the file attributes, but can execute the file. d. is the user who can change the file attributes, but cannot grant access to the file.
a. is the user who can change the file attributes and grant access to the file.
The consistency check is always able to recover the structures, e.g., resulting in loss of files and entire directories. Select one: a. True b. False
b. False
The logical file system module includes the free-space manager. Select one: a. True b. False
b. False
The open() call returns a pointer to the appropriate entry in the system wide-open-file table. Select one: a. True b. False
b. False
You can access a file in an unmounted file system. Select one: a. True b. False
b. False
For counting method (used by free space management), the entries in the free-space list can be stored in a linked list, rather than a balanced tree, for efficient lookup, insertion, and deletion. Select one: a. False b. True
a. False
Storage devices that do not allow overwrite (such as NVM devices) need only the free list for managing free space. Select one: a. False b. True
a. False
Solaris ZFS file system never overwrites blocks with new data. Select one: a. False b. True
a. False (According to the textbook, I thought it was True)
An operating system may provide: Select one: a. Many general-purpose file systems and one special-purpose file system b. Only one special-purpose file system c. Only one general-purpose file system and one special-purpose file system d. Only one general-purpose file system
a. Many general-purpose file systems and one special-purpose file system
A disk drive may have many partitions each of which contains a different file system. Select one: a. True b. False
a. True
An NFS (Network File System) is building on a RPC (Remote Procedure Call) system. Select one: a. True b. False
a. True
Contiguous allocation of a file is defined by the address of the first block and length (in block units) of the file. Select one: a. True b. False
a. True
The FAT method incorporates free-block accounting into the allocation data structure. Select one: a. True b. False
a. True
The I/O control level consists of device drivers and interrupt handlers to transfer information between the main memory and the disk system Select one: a. True b. False
a. True
The file allocation table (FAT) has one entry for each block and is indexed by block number. Select one: a. True b. False
a. True
In __________ write, the data are stored in the cache, and control returns to the caller. Select one: a. a synchronous b. a non-buffered c. an asynchronous d. a buffered
c. an asynchronous
A file owner can grant or remove the access to a given file. Select one: True False
True
At the boot time the system cannot interpret the file system format. Select one: True False
True
Files are stored in random-access storage devices. Select one: True False
True
In UNIX, a system configuration file, known as fstab (file systems table), includes information about files being mounted automatically at boot time. Select one: True False
True
It is possible to have a solution such that a given file system is mounted repeatedly at different mount points. Select one: True False
True
NFS "bridges" the Virtual File System of the client and the server across the network. Select one: True False
True
Part of the file system implementation has to include programmer API's such as read and write: Select one: True False
True
The local or remote file systems are the part of the third layer of virtual file system which is responsible for implementing file-system type or remote file system protocol. Select one: True False
True
To recover remote file server from failure a file server should know what files have been open by clients. Select one: True False
True
Logical-file system is responsible for both managing metadata information and protection: Select one: True False
True It is the Logical File System that brings the concepts of names, meta data, and permissions and protection to the file system.
What causes a lack of support for efficient direct (random) access in linked allocation: Select one: a. absence of FAT b. internal fragmentation c. declaration problems d. external fragmentation
a. absence of FAT
What is a significant drawback of a hash table: Select one: a. fixed size b. difficult insertion and deletion c. dependence on linear list structure d. slow read/write operations
a. fixed size
The advantage of continuous allocation lies in: Select one: a. flexibility b. easy management of memory space c. solving dynamic-storage allocation problem d. low number of required disk seeks
a. flexibility
The virtual file system layer: Select one: a. provides mechanisms for uniquely representing files b. maintains open file table c. allows access to the selected type of file d. provides mechanisms for uniquely representing filesis responsible for read(), write() calls
a. provides mechanisms for uniquely representing files
The addresses of a given number of free blocks can be found faster using linked list rather than using grouping. Select one: a. True b. False
b. False
What are the consequences of using clusters? Select one: a. They increase the number of blocks to manage and increase the amount of fragmentation b. The decrease the number of blocks to manage but increase internal fragmentation c. They increase the number of blocks to manage and decrease internal fragmentation d. They decrease the number of blocks to manage and decrease internal fragmentation e. They decrease the number of blocks to manage and increase external fragmentation
b. The decrease the number of blocks to manage but increase internal fragmentation
A directory entry MUST have: Select one: a. the name of the file b. a way to find the data associated with a file c. all the meta data for a file d. a file control block
b. a way to find the data associated with a file
Sequential access can be optimized by Select one: a. none of the other answers b. all of the other answers c. read-ahead technology d. free-behind technology
b. all of the other answers
The NFS protocol: Select one: a. does not provide concurrency control mechanisms except file locking. b. does not provide concurrency control mechanisms. c. provides concurrency control mechanisms. d. may provide concurrency control mechanisms.
b. does not provide concurrency control mechanisms.
A file may be associated with several images at the same time in: Select one: a. file systems consistent with UNIX Semantics. b. file systems consistent with Session Semantics. c. file systems consistent with NFS (Network File System) Semantics. d. file systems consistent with Windows Semantics.
b. file systems consistent with Session Semantics.
A linked free list uses no extra hard drive space, but has what drawback: Select one: a. you get a lot of internal fragmentation b. is harder to find contiguous free blocks c. that it takes more main memory d. that it is hard to code
b. is harder to find contiguous free blocks
Unified virtual memory uses _____________ to cache both process page and file data Select one: a. double caching b. page caching c. disk block caching d. buffer caching
b. page caching
Which is true about a linear list: Select one: a. can only be fixed size b. simpler to program c. faster to search d. harder to program than hash tables
b. simpler to program
Mounting a file systems means that: Select one: a. the file system is removed from the disk space. b. the file system is becoming available within the file system name space. c. the file system is becoming unavailable within the file system name space. d. the file system is being created in the disk space.
b. the file system is becoming available within the file system name space.
(Check all that apply) A volume control block is: Select one or more: a. contains information about how many files and directories there are b. usually stored at logical block 0 of the volume c. is only in memory d. contains basic information about the volume, including number of blocks, block size, and indices for the free space and root directory e. usually stored at the beginning of the physical hard drive
b. usually stored at logical block 0 of the volume d. contains basic information about the volume, including number of blocks, block size, and indices for the free space and root directory
Consistency semantics determines: Select one: a. How the information about files that are currently open is stored b. How modifications of data change the internal structure of a file system c. How modifications of data are observable to other users d. How the virtual file system layer maintains the internal file representation structure
c. How modifications of data are observable to other users
Consistency semantics determines: Select one: a. How the information about files that are currently open is stored b. How the virtual file system layer maintains the internal file representation structure c. How modifications of data are observable to other users d. How modifications of data change the internal structure of a file system
c. How modifications of data are observable to other users
The system-wide open-file table contains: Select one: a. only names of each open file b. a pointer to the file control block of each open file c. a copy of the file control block of each open file d. only names and addresses of each open file
c. a copy of the file control block of each open file
The following characteristics of disks make them convenient for being the secondary storage: Select one: a. it is possible to read a block from the disk, modify the block, and write it back into the same place b. none of the other answers c. all of the other answers d. a disk can access directly any block of information it contains
c. all of the other answers
UNIX inode is an example of _______ Select one: a. a contiguous allocation. b. an index file c. an indexed allocation d. a linked allocation
c. an indexed allocation
The root-partition: Select one: a. does not contain the operating system kernel, but it is the first mounted file system during the boot time. b. contains an operating system kernel and it is not necessary to be mounted. c. contains an operating system kernel and it is mounted during boot time. d. contains a list of the operating systems which may be booted.
c. contains an operating system kernel and it is mounted during boot time.
Which free space management approach takes advantage of the fact that multiple contiguous blocks may be allocated or freed simultaneously Select one: a. linked lists b. grouping c. counting d. space maps
c. counting
WAFL (write-anywhere file layout) Select one: a. cannot provide files via NFS b. can provide files via NFS, but not via CIFS c. is a distributed file system d. is a file system dedicated to single user operating systems
c. is a distributed file system
Which systems record each metadata update to the file system as a transaction Select one: a. consistency checking b. bootstrap restart c. journaling d. transaction monitor
c. journaling
The basic file systems _______________ Select one: a. tracks unallocated blocks and provides them the when it is required. b. manages directory structure. c. reads and writes physical blocks on the storage device. d. is responsible for protection.
c. reads and writes physical blocks on the storage device.
Stateless File Servers: Select one: a. are very secure. b. track which clients have exported volumes. c. require that each client request is self-contained, i.e., all information needed to locate the file and perform the requested operation is given. d. maintain states of all open files.
c. require that each client request is self-contained, i.e., all information needed to locate the file and perform the requested operation is given.
In file systems consistent with UNIX semantics: Select one: a. a file cannot be opened by one user only. b. users cannot share the pointer of current location into a file. c. writes to a file by a user are immediately visible to other users that have this file open. d. writes performed by one user are not seen by other users .
c. writes to a file by a user are immediately visible to other users that have this file open.
The average external fragmentation is: Select one: a. It is twice the block size b. It is 1/2 the total space minus the allocated space c. It is 1/2 the block size d. None of the other answers
d. None of the other answers There is no easy measure for external fragmentation as it is dependent on file sizes, creation and deletion activity and block sizes. On the other hand the average internal fragmentation is 1/2 the block size.
What information is required to mount a file system? Select one: a. The file system type and the mount point b. The name of the device containing file system and the file system type c. Only the name of the device d. The name of the device containing file system, file system type and the mount point
d. The name of the device containing file system, file system type and the mount point
A file handle is: Select one: a. a pointer to a logical address of a file b. a pointer to the file use directory c. a pointer to a physical address of a file d. a pointer to an entry in the per-process file system table
d. a pointer to an entry in the per-process file system table A file handle is an index or pointer to an in memory control bock used to keep track of a files information while open
Indexed allocation Select one: a. supports direct access b. does not suffer from external fragmentation. c. none of the other answers d. all of the other answers
d. all of the other answers
When the file system contains more than one bootable partition, then Select one: a. a boot loader is parallel searching each partition for kernel and runs the first found b. all available operating systems are booted at the same time c. the system cannot contain more than one bootable partition d. the system administrator (admin user) selects which operating system will be booted
d. the system administrator (admin user) selects which operating system will be booted
Which UNIX inodes and/or vnodes used by the Virtual File System (VFS) have a file representation structure? Select one: a. UNIX inodes are not unique designators for a single file system. b. vnodes are unique file designators for remote file systems only. c. UNIX inodes and vnodes are unique designators within a single file system only. d. vnodes are wide network unique file designators.
d. vnodes are wide network unique file designators.
LBA stands for Local Block Allocation? Select one: True False
False LBA stands for Logical Block Array, and it the virtual array of blocks presented by the Basic File System that represent the volume. We will use the terms Logical Block and Logical Block Array throughout the file system project
A computer system always has one file system. Select one: True False
False
In synchronous writes data is being stored in caches, with caller obtaining the control Select one: True False
False
Performance of allocation method is determined only by the used allocation algorithm: Select one: True False
False
Raw disk contains a file system. Select one: True False
False
The content of an immutable file can be changed. Select one: True False
False
Virtual file system does not distinguish local files from remote ones. Select one: True False
False
When a layered structure is used for file-system implementation, risk of duplication of code increases:
False
Server of NFS (Network File System) version 3 is stateful Select one: True False
False It is version 4 that implemented a stateful system, version 3 is stateless.