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Mod 7 part 2 > Day 6 > Flashcards

Day 6 Flashcards

1
Q

file systems

A

defines the way data is named, stored, organized, and accessed on a disk volume.
contain 5 layers: physical layer, file system layer, filename layer, metadata layer, data layer,

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2
Q

physical layer

A

physical file media; hard drive, cd/dvd, etc

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3
Q

file system layer

A

file system layout;

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4
Q

file name layer

A

user interface with file system. file names map to file metadata

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5
Q

metadata layer

A

file metadata containing allocation pointers and other descriptors.

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6
Q

data layer

A

each block/cluster is given a logical address where file data can be stored and located

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7
Q

FAT

A

the original file system.
has two versions: FAT (or FAT 16) and FAT32
the difference between the two is FAT16 root directory is fixed in place after FAT#2. FAT32’s root directory is located in the data area, like FAT16, but not in a defined location.
see page 83

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8
Q

boot sector

A

reserved area.
identifies the structural details of the FAT file systems
(file systems layer

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9
Q

FAT

A

allocation table that identifies cluster allocations. Two allocation tables are maintained for redundancy (FAT#1 and FAT#2) (metadata layer)

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10
Q

root directory

A

contains directory entries for all files and folders (filename and metadata layers)

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11
Q

data area

A

stores the root directory and file data (data layer)

FAT16 file systems root directory is located directly after FAT #2.

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12
Q

allocation table

A

the FAT identifies cluster allocations and manages the linked allocation for files

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13
Q

FAT16

A

16-bit table entries that can allocate 65,536 clusters

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14
Q

FAT32

A

32-bit table entries that can address 200+ million clusters (4 bits reserved)

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15
Q

linked allocation

A

the table entry contains the cluster address where the next piece of the file is located.
Each piece of the file is linked along until the end of file (EOF) is reached (FFFF is the EOF marker for FAT16)
see figure 47 on p84

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16
Q

bad clusters in FAT

A

FAT 16 bad cluster 0xFFF7

FAT32 bad cluster 0xFFFFFFF7

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17
Q

directory entry

A 
every file on a FAT volume has a 32-byte directory entry containing information such as file name, starting cluster address, size, file attributes (i.e. RASH) and timestamps
R-read only
A-archive
S-system
H-hidden
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18
Q

filenames

A

stored in the directory entry using the 8.3 naming convention, using eight characters for the name of the file and three characters for the file’s extension. File names longer than eight characters are truncated.
ex. THISISMYFILE.txt is truncated to THISIS~1.txt

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19
Q

long file name (LFN)

A

support up to 255 characters for path and filename is provided by linking multiple directory entries together

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20
Q

starting cluster

A

the directory entry contains the STARTING CLUSTER address for the first piece of the file. if the file requires multiple clusters, the FAT is sued for the linked allocation metadata

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21
Q

file size

A

the file size identifies the space required to store the file in the data layer

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22
Q

file attribute

A

file attribute status is stored in the 12th byte of the directory entry.

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23
Q

time stamps

A

there are three main timestamps stored in the directory entry: created, accessed, and written/modified.

24
Q

created

A

set when a new directory entry is made or time a file was created in its present location

25
Q

accessed

A

FAT file systems access timestamp is only accurate to the day. there is not enough room in the 32-byte directory entry to track an access time.
accessing file properties or opening a file for viewing updates this time.
files that are moved to another volume will have their content accessed and read prior to being updated.

26
Q

written (modified)

A

updated when new file content is written.
time is based on content, not directory entry creation.
time remains the same as data is moved and copied.

27
Q

step 1

A

create file results in a new directory entry

28
Q

step 2

A

locate directory and starting cluster where the file will reside by processing entries until an unallocated directory entry is located. Write filename, size, and create time in new directory entry.

29
Q

step 3

A

search the FAT to find an available cluster and set its value to EOF.

30
Q

step 4

A

update directory entry with the starting cluster. fi the file is larger than the size of the cluster, a second cluster is located in FAT, and OEF is marked there.

31
Q

step 5

A

update first cluster with the location of the second cluster.

32
Q

file deletion

A

step1. locate directory entry and process clusters until the file is found.
step 2. change first byte in directory entry to 0xE5 and set all FAT cluster entries to 0. Data is physically still there; only the reference to it is gone.

33
Q

file copy.

A

when a file is copied within the same volume or between two volumes, a new directory entry is created requiring new cluster allocations (s). The new file has a new creation time while retaining the original written time.

34
Q

file move

A

the original written and creation time is retained when moved within the same volume. If moved to a different volume, a new directory entry is created requiring new cluster allocations. The file has an updated creation time while retaining the original written time.

35
Q

NTFS

A

the most common file system offered by Microsoft Windows

36
Q

Key features of NTFS

A

compression
encryption
disk quotas are set on a per-volu

37
Q

Key features of NFTS

A

compression
encryption
disk quotas are set on a per-volume, per-user basis
file and folder security….permissions!
mounted volumes
reliability using transaction-based logging

38
Q

Two registry keys

A

HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDLG32\LastVisitedPidlMRU

contains the names of recently used executable files and their paths

39
Q

and….

A

HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDLG32\OpenSavedPidlMRU

contains list of all recently opened or saved files organized in sub-keys based on their file extension

40
Q

Master File Table (MFT)

A

NTFS uses the MFT to manage filename and metadata for the NTFS file system and is considered the heart of the file system.

41
Q

$MFT

A

First MFT entry which shows disk location of the MFT (entry 0). There is a backup copy, $MFTMirr (entry 1)

42
Q

$LogFile

A

used for transaction-based logging (entry 2)

43
Q

$Volume

A

Contains information about the volume (entry 3)

44
Q

.

A

Root directory of the file system C:\ (entry 5)

45
Q

$Bitmap

A

used to allocate clusters in the volume (entry 6)
allocated (bit value-1)
unallocated (bit value-0)

46
Q

$Boot

A

contains location and description of boot sector used when system is started (entry 7)

47
Q

$BadClus

A

Used to mark bad clusters (entry 8). When a bad cluster is found, it will be marked with a bit-value of 1. The size of this file is unlimited.

48
Q

$Secure

A

used as a security settings file (entry 9)

49
Q

MFT entry

A

each MFT entry is subject to a 1KB size constraint .

50
Q

resident

A

a resident attribute is stored completely within the MFT entry.
<1K

51
Q

non-resident

A

a non-resident attribute’s data is stored outside of the MFT entry
>=1K

52
Q

Common mft entry attributes for files and directories

A

.

53
Q

$Standard Information ($SIA)

A

Resident attribute that provides the most accurate timestamps and file attributes such as archive, hidden, and read-only

54
Q

$File_Name

A

Resident attribute that contains a reference to the parent directory. It also contains the file name, size, and inherits the time stamps from the $Standard_Information attribute. ($SIA)

55
Q

$DATA

A

Contains file data or a pointer to the location of file data. may be either resident or non-resident

56
Q

VCN to LCN mapping

A

Virtual cluster number (VCN) identifies how many clusters are needed. Always starts with 0 and is used to keep the pieces in order.

Logical Cluster number (LCN) identifies the cluster address

Similar to FATS linked allocation

57
Q

NTFS Timestamps

A

Creation time - timestamp when file was created, based on MFT entry
Modified Time- Timestamp when the contents of $DATA attribute was last modified.
MFT Modified Time–Timestamp when file MFT entry metadata was last modified; also known as change time.
Accessed Time–Timestamp when file was last accessed. (accurate to the second)

Mod 7 part 2 (6 decks)

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