Storage Management

Question 1

File

Answer 1

Contiguous logical address space; abstract data type

Question 2

Types of files

Answer 2

Data numeric character binary Program Read/write depending on type of file

Question 3

File operations

Answer 3

Create Write Read Reposition within file Delete Truncate Open(Fi) – search the directory structure on disk for entry Fi, and move the content of entry to memory Close (Fi) – move the content of entry Fi in memory to directory structure on disk

Question 4

File attributes

Answer 4

Name – only information kept in human-readable form Identifier – unique tag (number) identifies file within file system Type – needed for systems that support different types Location – pointer to file location on device Size – current file size Protection – controls who can do reading, writing, executing Time, date, and user identification – data for protection, security, and usage monitoring Information about files are kept in the directory structure, which is maintained on the disk

Question 5

File system organization

Answer 5

Partition contains directory and files Root, top level for structure

Question 6

File system mounting

Answer 6

file system must be mounted before it can be accessed

Question 7

File directory operations

Answer 7

each operation changes structure Search for a file Create a file Delete a file List a directory Rename a file Traverse the file system

Question 8

File control block

Answer 8

File permissions File dates File owner, group, ACL File size File data blocks or pointers to file data blocks

Question 9

File allocation methods

Answer 9

Contiguous allocation Linked Allocation Indexed Allocation

Question 10

File specification standards

Answer 10

Name conventions Functions to implement What media to use SCSI - small computer system Examples: FAT16 - file access table, MSDOS, 16 bit, 8+3 names FAT32 - file access table (windows), short names NTFS ex FAT

Question 11

File System Implementation

Answer 11

Group of sectors, sector = 512 bytes Fragmentation (holes) addressed in file linking in file partition table Disk sizes growing, 512 bytes meaningless Clusters - 8 sectors, or user defined

Question 12

Directory Implementation

Answer 12

1. Linear list (linked list or B tree) 2. Hash table (if collision, set up linked list)

Question 13

Raw partition file system

Answer 13

no file system,no files; write directly to sectors

Question 14

Contiguous allocation

Answer 14

similar to contiguous memory, same issues each file occupies set of blocks on disk simple; need start loc + number of blocks random access access times better do not need to search for files just need start and end address wastes space, files cannot grow creates holes; need to shuffle, compact, defrag

Question 15

Extant based systems

Answer 15

modified contiguous allocation

Question 16

Linked allocation

Answer 16

Avoids contiguous problems (holes and wasted space) file is a linked list of blocks simple, no waste space used by FAT; FAT 1 one FAT table FAT2 2 FAT tables, one as backdrop but no random access, must navigate through linked list

Question 17

Indexed allocation

Answer 17

all pointers brought together in index block need index table (con); pointers require blocks, can run out of space random access dynamic access without external fragmention

Question 18

File access methods

Answer 18

Sequential or direct