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Reckoner-Assisted Attacks and Crimes

In The Official CHFI Study Guide (Exam 312-49), 2007

Investigating Lawmaking Injection Attacks

Evidence of a code injection attack is rarely found in the Web server logs. If the Web designer writes failed input data to a log file, you will probably see the various attempts to become the assault right. If there are no logs of incorrect attempts to fill up out a form or other inputs, you may have to resort to network traffic sniffer logs.

Using an open source tool such as Wireshark to capture traffic going to the server so searching for either all requests going to the input folio or field names on the page may give yous a adept accounting of the malicious traffic and the IP address of the source.

You lot may take to assemble some rather big files to catch one of the attempts. By setting the capture filter on the sniffer of your choice to just the traffic going to the server you tin reduce the capture file considerably.

In Wireshark the capture filter would be dst host xxx.xxx.thirty.xxx (the x's are the IP address of the server). Note that you should test to see how big this file gets over the space of an hr or two and make sure you lot have sufficient storage infinite for the resulting file before you lot leave the sniffer running unattended for long periods.

Head of the Class…

Wireshark File Sizes

The creators of Wireshark and its predecessor, Ethereal, knew that files can become large in a hurry, so they have a few helpful items in the Capture dialog box. Yous can set limits to file sizes in several different ways.

You can fix the maximum file size to a specific number of bytes, kilobytes, or megabytes.

Y'all can set the maximum number of minutes or hours that the capture runs.

Yous can set the files to break into smaller chunks so that they fit on a CD or DVD easily.

Knowing these options and using them as you see fit during traffic capture sessions can mean the difference between having all the information yous need for an investigation and exposing yourself to some serious headaches.

For more helpful hints on Wireshark, run across the wiki at http://wiki.wireshark.org.

If you know that one of the input fields on a page you are investigating is labeled homePhone, you lot can use the frame contains display filter frame contains "homePhone". Whatsoever packets that take information going to the input field will be shown and tin can exist examined for proper or malicious content.

Other locations of testify may exist found in access logs or transaction data. Don't forget to wait at transaction times as well. If you lot are seeing a big number of transactions in a short period, or at odd hours, yous may be seeing signs of an assault.

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Managing Users

Tony Redmond , in Microsoft Exchange Server 2007 with SP1, 2008

8.five.6 Logging Managed Folder activity

By default, Exchange 2007 does non log any details of the work performed by the Managed Folder Assistant. If you want to gain some insight into what happens when the Managed Folder Assistant runs, you can enable logging on a mailbox server with the Prepare-MailboxServer command. For case:

After you enable logging, Exchange generates daily log files in the \Program Files\Microsoft\Substitution Server\Logging\Managed Folder Assistant directory. Like to the parameters available to command bulletin tracking logs, y'all can change how Exchange manages these log files.

In this command, we set a number of parameters.

▪: The full size limit for the directory that stores the managed folder banana log files is prepare to 100MB. Later Exchange reaches this limit, it deletes the oldest log files to make room.
▪: The age limit for log files is gear up to 30 days. Exchange deletes log files that are older than the limit.
▪: The maximum file size for a managed folder banana log is prepare to 25MB (the default is 10MB). After the log file reaches the specified size, Exchange creates a new log. Note that the 10MB default limit is more than than sufficient for the vast bulk of servers.
▪: The location where Exchange creates log files for the Managed Folder Banana is moved abroad from the default on the organization disk. It is best practice to movement all log files generated past Exchange off the system disk.
▪: Substitution is instructed to log information most messages that have reached their retentivity limit.
▪: Substitution is instructed to log the subject for whatever message that is candy by the Managed Binder Assistant.

Figure 8-38 illustrates some example content extracted from a managed folder assistant log. Three actions are highlighted:

1.: The Managed Folder Assistant has processed an detail that is by its retention date.
2.: The Managed Folder Assistant has journaled an item in a managed folder.
3.: The Managed Folder Assistant is processing a mailbox to use a managed binder policy.

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Maintaining Hard Disks

In How to Crook at Windows Arrangement Administration Using Command Line Scripts, 2006

Supported File Systems

Windows XP and Windows Server 2003 back up the following types of file systems:

▪: Fat file system The File Allocation Tabular array (Fatty) file system is the original file system used past MS-DOS and other Windows operating systems. It is a data structure Windows creates when a book is formatted. This construction stores data nearly each file and directory then that information technology tin be located subsequently. The maximum disk partition size is iv GB. On floppy disks, this is limited by the chapters of the disk. The maximum supported file size on hard disks is 2 GB.
▪: FAT32 file system FAT32 stands for File Allocation Table32, an avant-garde version of the FAT file arrangement. The FAT32 file system supports smaller cluster sizes and larger volumes than the Fat file system, which results in more than efficient space allocation. FAT32 file systems back up a maximum partition size of 32 GB for Windows XP and Windows Server 2003. The maximum size file size is 4 GB.
▪: NTFS NTFS, which stands for New Engineering science File System, is an avant-garde file organisation that provides performance, security, reliability, and avant-garde features not found in FAT and FAT32 file systems. Some of the features of NTFS include guaranteed book consistency by ways of transaction logging and recovery techniques. NTFS uses log file and checkpoint information to restore the consistency of the file system. Other advanced features of NTFS include file and folder permissions, pinch, encryption, and disk quotas. You cannot use NTFS on floppy disks due to its express capacity (Sysinternals has a utility for using NTFS on floppy disks. For more information check out Syngress Publishing's Winternals Defragmentation, Recovery, and Assistants Field Guide, ISBN 1-59749-079-2). The maximum supported partition size ranges from 2 TB to 16 TB. The maximum file size can be up to 16 TB minus 16 KB. The minimum and maximum partition sizes vary by the partition way chosen when the operating organization was installed.

Formatting a Deejay or Partition with the Format Control

A hard disk or a partition is of no use to whatsoever operating arrangement unless information technology is formatted. You use the Format command to format raw disks or disk partitions with a selected file organisation. You tin can use the Fatty, FAT32, or NTFS file system when formatting a disk with Windows XP and Windows Server 2003 operating systems. When a disk is formatted, all data on the disk is lost, just the Format control displays a warning bulletin before it starts. After the deejay is formatted, a new root directory and the specified file system are created on the disk. The syntax of this control is:

Table 5.one explains the parameters of this control.

Table 5.ane. Parameters of the Format Control

Parameter	Clarification
Book:	Specifies the drive, volume, or mounted book that y'all wish to format. The drive alphabetic character is followed by a colon (:).
/fs.FileSystem	Specifies the file system to use for formatting. This parameter supports the FAT, FAT32, and NTFS file systems. When you are using this command for floppy disks, you can apply only the Fatty file organisation.
/v.Label	Used to assign a label to the formatted book. If you practise not utilize it, or if you use information technology without specifying the characterization, the Format command prompts you to specify a label once the formatting is complete.
/q	Used to perform a quick format of a previously formatted book. It causes the command to delete the existing root directory and file table and cuts the fourth dimension required to format a disk when you are certain that information technology does non have any bad sectors.
/a.UnitSize	Used to specify the resource allotment unit size for disk clusters.
/c	Used only with NTFS file systems. Information technology automatically compresses all files created on the new volume.
/x	Used to dismount the mounted volume (if required) during the formatting process.
/f:Size	Used for floppy disks to specify their size. Accepted parameters include one,440, 1,440 k, 1,440 KB, 1.44, ane.44 M, and 1.44 MB. It is preferred over the /t:Tracks and /n:Sectors parameters.
/t:Tracks /n:Sectors	Used together to specify the number of tracks (/t:Tracks) and sectors per runway (/n:Sectors) on the disk. Microsoft recommends that yous utilise the /f:Size parameter instead of using these two parameters together. When you apply /f:Size to define the size of the disk, you cannot use the /t:Tracks or /north:Sectors parameter.

Allocation Unit Size

You lot can specify the size of the allocation unit with the Format command by using the /a:UnitSize parameter. Each hd is fabricated up of small units known as sectors or clusters. The allocation unit of measurement size defines the number of bytes per cluster on the formatted deejay. The following is a list of the supported allocation unit sizes for the Fatty, FAT32, and NTFS file systems:

▪: 512 Sets the unit size to 512 bytes per cluster.
▪: 1024 Sets the unit size to 1,024 bytes per cluster.
▪: 2048 Sets the unit of measurement size to ii,048 bytes per cluster.
▪: 4096 Sets the unit size to 4,096 bytes per cluster.
▪: 8192 Sets the unit size to 8,192 bytes per cluster.
▪: 16K Sets the unit size to 16 kilobytes (16 KB) per cluster.
▪: 32K Sets the unit size to 32 kilobytes (32 KB) per cluster.
▪: 64K Sets the unit size to 64 kilobytes (64 KB) per cluster.

When you do not use the /a:UnitSize parameter with the Format command, the system chooses an appropriate unit of measurement size based on the size of the volume.

Principal Craftsman …

Cluster Size and Number of Clusters

The advantage of using smaller sizes for disk clusters when formatting a disk or a sectionalisation is the cosmos of pocket-size placeholders for files on the disk. Smaller cluster sizes are very useful in situations where you lot need to store a large number of small files on a disk with express storage capacity. This helps reduce wasted infinite on modest disks when you are creating clusters of sizes every bit large as 64 KB. Another limitation of large cluster size on NTFS partitions is that you cannot utilize NTFS compression if the cluster si2e is larger than 4,096 bytes (or 4 KB).

The number of clusters is also limited in Fat and FAT32 volumes. With Fatty volumes you can have a maximum of 65,526 clusters and with FAT32 volumes you can take between 65,527 and 4,177,917 clusters.

WARNING

The following department contains some examples of the Format command. Practise not use this command on any production figurer considering it will delete all data on the disk or division y'all specify. Even when you are trying this control on a examination computer, make sure that you back upwardly all data commencement.

Examples of the Format Command

The post-obit are some examples of the Format command:

The first control formats the floppy disk in the computer'south A: drive with all default settings. The 2d control formats the floppy disk and assigns information technology the Backup characterization. When yous do not use the /v:label parameter or practice not specify a volume label with the /v parameter, the following bulletin is displayed after the floppy disk is formatted:

You tin enter a label for the floppy disk or press the Enter key if y'all do not want to apply one. Since a floppy drive is formatted in the given example, and floppy disks back up only the Fatty file system, the number of characters you can include in the characterization is limited to 11. Here are two more examples:

The first command performs a quick format of the E: drive with the NTFS file system. The second command formats the F: drive with the FAT32 file system and an resource allotment unit size of 512 bytes. Earlier the control starts formatting a partition on the hard disk, it displays the following alert message:

This is your run a risk to cancel the Format command, if you accept used it past fault or selected a wrong partition to format. Press the Y key if you want to go along with the format or press the N fundamental to abort the control. During the format process, the control displays its progress equally a percent of the total deejay infinite formatted. When formatting is complete the Format control displays the total deejay space and the bachelor disk space in kilobytes (KB).

If yous desire the newly formatted book to compress all files stored in it, y'all tin can use the /c parameter. This feature is available on NTFS volumes only. Here is an example:

Later on the book is formatted, all files created on the E: book will be automatically compressed.

NOTE

You lot cannot employ the Format command over the network to format a deejay on a remote estimator. Fifty-fifty on a local computer you must have authoritative rights to utilise the Format command.

Leave Codes for the Format Control

The Format command comes with its own set of leave codes that bespeak the success or failure of the control, and the reason for failure. When you apply the Format command in a batch file, you tin control the process by using the leave codes it generates. Exit codes are normally used as arguments with the Errorlevel parameter in if and goto statements for conditional processing of batch file commands. Table five.two lists the exit codes for the Format command.

Table 5.2. Go out Codes for the Format Command

Exit Code	Clarification
0	The format process completed successfully without errors.
1	Incorrect parameters were supplied with the Format command.
4	A fatal error occurred during the format procedure. This may be any error other than errors 1, iv, and 5.
five	The user pressed the N central to finish the format process when prompted with the question, "Proceed with Format (Y/N)?"

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Assay of Operating System Components

Paul J. Fortier , Howard E. Michel , in Computer Systems Functioning Evaluation and Prediction, 2003

13.two.2 Windows XP architecture

Windows XP Professional is built on the proven code base of operations of Windows NT and Windows 2000, which features a 32-scrap calculating architecture, as well as a fully protected memory model. Windows XP Professional is designed to permit multiple applications to run simultaneously, while ensuring bang-up organization response and stability.

Disk management

Microsoft Windows XP offers ii types of disk storage: basic and dynamic.

Basic disk storage

A disk initialized for basic storage is chosen a basic deejay. A basic disk contains basic volumes, such equally primary partitions, extended partitions, and logical drives. Additionally, basic volumes include multidisk volumes, which are created by using Windows NT iv.0 or before, such as volume sets, stripe sets, mirror sets, and stripe sets with parity. Windows XP does not support this multidisk basic volume.

Dynamic deejay storage

A disk initialized for dynamic storage is called a dynamic disk. A dynamic disk contains dynamic volumes, such as simple volumes, spanned volumes, striped volumes, mirrored volumes, and RAID-5 volumes. With dynamic storage, disk and volume management tin exist performed without the need to restart Windows. Mirrored volumes or RAID-5 volumes cannot exist created on Windows XP Professional-based computers. Notwithstanding, a Windows XP Professional-based computer tin be used to create a mirrored or RAID-five book on remote computers that are running Windows 2000 Server, Windows 2000 Advanced Server, or Windows 2000 Data Centre Server.

Storage types are separate from the file organisation type. A basic or dynamic disk tin comprise any combination of FAT16, FAT32, or NTFS partitions or volumes.

File systems

Windows XP supports three different file systems: File Allocation Tabular array (Fat); FAT16, FAT32, and NTFS (NT file arrangement); NTFS is the recommended file organisation. NTFS provides advanced file system features such as security, transacted operations, large volumes, and better functioning on large volumes. Such capabilities are not available on either FAT16 or FAT32. Windows XP provides native support for NTFS volumes on such large sizes, while a FAT32 volume is supported only for sizes up to 32 GB. Nether Windows XP, NTFS supports a maximum file size of up to the disk size. Windows XP delivers new features (such equally back up for acquiring and editing video files) that frequently event in cosmos of files that exceed 4 GB in size. NTFS is a journaling file arrangement. NTFS writes a log of changes being made, which offers significant benefit in cases where a organization loses power, experiences an unexpected reset, or crashes. NTFS can quickly render the disk to a consistent state without running CHKDSK. This yields a ameliorate user feel and results in fewer support calls.

Memory management

Windows XP, similar most modern operating systems, uses virtual memory. Windows XP regularly checks that the retentivity assigned to a particular application is really in use and maintains an estimate for each application indicating the amount of retention that could reasonably be taken away without affecting performance. A reserve of memory is kept on manus to be used every bit needed. When this reserve sinks too depression, it is replenished by trimming working sets. These estimates are used every bit a guideline to determine where memory should be taken from.

Virtual retentiveness is divided amid the space taken by the applications, driver code, allocated and mapped data used past the system, and the space used by the system. In Windows, physical retention has page-pooled and non-folio-pooled allocations. Not-page-pooled memory is for code that is fourth dimension critical, such as the Virtual Memory Managing director (VMM). Page-pooled retentiveness is mapped to disk files and allows the Os to swap the retentivity pages out to disk if additional physical memory is needed elsewhere. Puddle memory is managed by a system of descriptors, called page tabular array entries (PTE), that incorporates memory page frame numbers which signal to physical retentiveness pages. In addition to memory page frame numbers, the PTE contains $.25 on the use status of the folio—in utilise, dirty, make clean, and unused. The retention managing director keeps track of page status with page table lists for fetching and reuse.

In the fight between drivers or processes for memory under low-memory conditions, the user oft loses. Generally, these conditions are temporary and are relieved when a driver or process frees up its blocks. When a driver or awarding procedure needs memory, it asks the organisation for a memory allocation. The resource allotment is either provided or denied. In past versions of Windows, allocation routines that must succeed were allowed to force the arrangement to give the commuter some retentivity. Unfortunately, during lean retentiveness times, it could crash the organisation. To help get past these low times, Windows XP no longer permits drivers to classify must-succeed requests. If an application or driver uses a must-succeed request, it is denied. All internal Windows XP drivers accept been rewritten to avert the use of must-succeed requests. Third-political party drivers volition also have to comply to earn signed driver condition.

Some other step taken by Windows XP for more robust memory handling is I/O throttling. For performance reasons, Windows tries to do as much processing in parallel equally possible. Notwithstanding, if memory use gets to the point where there is none left to classify, Windows volition throttle down its processing of retention to 1 folio a time, using the resources it can. While this slows the system, it doesn't crash.

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Cloud Data Storage

Dan C. Marinescu , in Cloud Computing (2d Edition), 2018

6.4 General Parallel File Arrangement

Once the distributed file systems became ubiquitous, the natural next step in the file systems development was supporting parallel access. Parallel file systems permit multiple clients to read and write concurrently from the same file. Support for parallel I/O is essential for the performance of many applications [334]. Early supercomputers such as the Intel Paragon took advantage of parallel file systems to support data-intensive applications.

Concurrency control is a critical issue for parallel file systems. Several semantics for treatment shared and concurrent file access are possible. I option is to take a shared file pointer. In this case successive reads issued past different clients advance the file pointer. Some other semantics is to allow each client to have its ain file arrow.

The General Parallel File System (GPFS) [444] was adult by IBM in early 2000s as a successor of the TigerShark multimedia file arrangement [226]. GPFS is a parallel file system emulating closely the behavior of a full general-purpose POSIX system running on a single arrangement. GPFS was designed for optimal performance of large clusters. GPFS can support a file organization of upwardly to 4 petabytes consisting of up to $4 096$ disks of ane TB each, see Figure 6.6 . The maximum file size is ${ii}^{63} - 1$ bytes.

A file consists of blocks of equal size, ranging from 16 KB to 1 MB stripped across several disks. The system could back up non simply very large files, but likewise a very large number of files. GPFS directories utilise the extensible hashing techniques to access a file. A hash role is applied to the name of the file; then the n depression-lodge bits of the hash value requite the cake number of the directory where the file information can be plant, with n a office of the number of files in the directory. Extensible hashing is used to add a new directory block. The organisation maintains user information, file metadata, such as the fourth dimension when last modified, and file system metadata, such as allotment maps. Metadata, such as file attributes and data block addresses, is stored in inodes and in indirect blocks.

Reliability is a major concern in a system with many concrete components. To recover from system failures GPFS records all metadata updates in a write-ahead log file. Write-ahead means that updates are written to persistent storage only after the log records accept been written. For case, when a new file is created, a directory bloc must be updated and an inode for the file must be created. These records are transferred from cache to disk afterwards the log records have been written. When the organization ends up in an inconsistent state, the directory bloc is written and then if the I/O node fails earlier writing the inode, the log file allows the system to recreate the inode tape. The log files are maintained by each I/O node for each file organization information technology mounts and any I/O node is able to initiate recovery on behalf of a failed node. Deejay parallelism is used to reduce the access time; multiple I/O read requests are issued in parallel and data is pre-fetched in a buffer pool.

Data striping allows concurrent admission and improves performance, but can take unpleasant side-furnishings. Indeed, when a single disk fails, a large number of files are afflicted. To reduce the impact of such undesirable events, the arrangement attempts to mask a single disk failure or the failure of the access path to a disk. The system uses RAID devices with the stripes equal to the block size and dual-attached RAID controllers. To further amend the mistake tolerance of the system GPFS data files, equally well as metadata, are replicated on two different physical disks.

Consistency and performance, critical for whatsoever distributed file system, are difficult to balance. Support for concurrent access improves performance, but faces serious challenges for maintaining consistency. GPFS consistency and synchronization are ensured past a distributed locking machinery. A primal lock manager grants lock tokens to local lock managers running in each I/O node. Lock tokens are too used past the cache management system.

Lock granularity has important implications on the performance of a file organization and GPFS uses a variety of techniques for different types of data. Byte-range tokens are used for read and write operations to data files equally follows: the showtime node attempting to write to a file acquires a token covering the unabridged file, $[0, \infty]$ . This node is allowed to comport out all reads and writes to the file without any demand for permission until a second node attempts to write to the same file; then, the range of the token given to the outset node is restricted. More precisely, if the offset node writes sequentially at first $f p_{ane}$ and the second one at offset $f p_{two} > f p_{1}$ , then the range of the tokens for the two tokens are $[0, f p_{2}]$ and $[f p_{ii}, \infty]$ , respectively, and the ii nodes can operate concurrently without the need for farther negotiations. Byte-range tokens are rounded to block boundaries.

Byte-range token negotiations among nodes use the required range and the desired range for the start and for the length of the current and the future operations, respectively. The information-shipping, an alternative to byte-range locking, allows fine-grain information sharing. In this manner the file blocks are controlled by the I/O nodes in a round-robin style. A node forwards a read or write functioning to the node controlling the target block, the merely ane allowed to access the file.

A token manager maintains the country of all tokens; it creates and distributes tokens, collects tokens once a file is closed, downgrades/upgrades tokens when additional nodes request access to a file. Token management protocols attempt to reduce the load identify on the token manager; for example, when a node wants to revoke a token it sends messages to all the other nodes holding the token and frontward the reply to the token manager.

Access to metadata is synchronized; for example, when multiple nodes write to the same file, the file size and the modification dates are updated using a shared write lock to access an inode. I of the nodes assumes the role of a metanode and all updates are channeled through information technology; the file size and the final update time are adamant past the metanode subsequently merging the private requests. The same strategy is used for updates of the indirect blocks. GPFS global data such as ACLs (Access Control Lists), quotas, and configuration data are updated using the distributed locking mechanism.

GPFS uses disk maps for the management of the disk space. The GPFS block size can be as large as one MB and a typical block size is 256 KB. A block is divided into 32 sub-blocks to reduce disk fragmentation for small files thus, the cake map has 32 $.25 to signal if a sub-bloc is free or used. The system disk map is partitioned into north regions and each disk map region is stored on a dissimilar I/O node; this strategy reduces the conflicts and allows multiple nodes to allocate disk space at the same time. An allotment director running on i of the I/O nodes is responsible for actions involving multiple disk map regions. For case, information technology updates free space statistics, helps with deallocation by sending periodically hints of the regions used by individual nodes.

A detailed discussion of organisation utilities and of the lessons learned from the deployment of the file arrangement at several installations in 2002 can exist found in [444]; the documentation of the GPFS is available from [247].

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Video Direction Systems

Vlado Damjanovski , in CCTV (Third Edition), 2014

The different file systems

Each different operating system uses some kind of file system in order to write information on hard drives and removable media, so that afterwards on the user is able to detect it and read information technology. Inherently, this is a fundamental and important concept that defines the flexibility, capacity, and security of various systems. This is why we will mention the most mutual ones here.

All file systems consist of structures necessary for storing and managing data. These structures typically include an operating organization kicking record, directories, and files.

A file system performs three main functions: it tracks the allocated and unused space; it maintains directories and filenames; and it tracks the physical coordinates where each file is stored on the disk.

Different file systems are used past dissimilar operating systems. Some operating systems (such as Windows) can recognize only some of its own file systems, while others (such every bit Linux and Mac OSX) tin recognize several, including file systems from another OS.

1 important case of this interchangeability is the USB keys, or wink-disks, as they are sometimes called. Typically, a USB storage device is formatted with Microsoft'due south FAT32, but information technology can be read by almost all OS. But, the FAT32 comes with its own limitations, such equally the maximum file size in i block, or the maximum chapters it can address. This may somewhen impact some exporting capability from some machines, then installers and integrators should exist aware of such limits.

It is likewise important to mention that some manufacturers use raw information writing on hard disks without formatting them. This allows for quick installation of new drives when the old ones fail, equally it does non crave time-consuming formatting. Other manufacturers have their own formatting method where video data is written sequentially, thus making the USB storage device quicker in searching and playback.

Some of the near common file systems in employ today are:

Ext/ext2/Ext3/Ext4 – Extended file system, designed for Linux systems

Fatty – Used on DOS and Microsoft Windows, working with 12 and 16 $.25

FAT32 – Fat with 32 $.25

HFS/HFS + – Hierarchical File System, used on Mac OS systems

HPFS – High Performance File system, used on IBM'due south Bone/two

ISO 9660 – Used on CD and DVD-ROM disks on a diverseness of platforms

GPFS – IBM Journaling File system, provided in Linux, Windows and AIX

NTFS – Used on Windows NT-based systems (Windows 2000, XP, seven)

ReiserFS/four – File arrangement that uses journaling, used in Linux and Unix

FATX – Used in Microsoft's X-Box

LTFS – IBM's file system for Linux, Mac OSX and planned for Microsoft Windows

ReFS – Microsoft's new 2012 Server file organization

Subsequently in this affiliate we are going to address the near mutual file systems in CCTV workstations, servers, DVRs, and NVRs more in-depth.

FAT (File Allocation Table)

Introduced past Microsoft in 1983, the File Resource allotment Table (Fat) is a file organization that was developed for MS-DOS and used in consumer versions of Microsoft Windows up to and including Windows ME. Fifty-fifty with 512-byte clusters, this could give up to 32 MB of space – enough for the 10 MB or twenty MB XT hard drives that were typical at the fourth dimension. As hard drives larger than 32 MB were released, large cluster sizes were used. The use of 8192-byte clusters immune for file system sizes up to 512 MB. However, this increased the problem of internal fragmentation where small files could consequence in a great deal of wasted space; for instance, a 1-byte file stored in a 8192-byte cluster results in 8191-bytes of wasted space.

The Fatty file organization is considered relatively unproblematic, and because of that, it is a pop format for floppy disks. Moreover, it is supported by nearly all existing operating systems for personal computers, and considering of that it is often used to share information between several operating systems booting on the aforementioned computer (a multi-kicking surroundings). It is also used on solid-country retention sticks and other similar devices.

The Fatty file system as well uses a root directory. This directory has a maximum allowable number of entries and must exist located at a specific place on the disk or partition.

Although it is i of the oldest file formats, FAT is likely to remain in use for a long time because it is an ideal file system for small drives. It is also used on other removable storage for noncomputer devices, such every bit wink memory cards for digital cameras, USB wink drives, and the like.

FAT32 (File Resource allotment Table 32-fleck)

In 1997, Microsoft created FAT32 every bit an extension to the Fatty concept because the cluster growth possibility was wearied. The FAT32 was an enhancement of the Fat file system and was based on 32-fleck file allocation tabular array entries, rather than the sixteen-fleck entries used by the previous FAT organisation. Equally a result, FAT32 supports much larger disk or partition sizes (up to ii TB). This file organization can be used by Windows 95 SP2 and Windows 98/2000/XP. Previous versions of DOS or Windows cannot recognize FAT32 and are thus unable to kicking from or use files on a FAT32 deejay or partition. The FAT32 file system uses smaller clusters than the FAT file arrangement, has indistinguishable boot records, and features a root directory that tin can be of any size and can be located anywhere on the disk or partition. The maximum possible size for a file on a FAT32 book is four GB. Video applications, large databases, and some other software easily exceed this limit which is the reason some DVRs/NVRs exporting to USB keys break up the files to such sizes.

The FAT32 cluster values are represented by 32-chip numbers, of which 28 bits are used to hold the cluster number. The boot sector uses a 32-bit field for the sector count, limiting the FAT32 volume size to 2 TB for a sector size of 512 bytes and 16 TB for a sector size of 4,096 bytes. FAT32 was introduced with Windows 95 in 1996, although reformatting was needed to use it, and DriveSpace 3 (the version that came with Windows 95 OSR2 and Windows 98) never supported it. Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of information. In the Windows NT line, native support for FAT32 arrived in Windows 2000. In theory, this should back up a full of approximately 268,435,438 clusters, allowing for drive sizes in the multi-terabyte range. Withal, due to limitations in Microsoft'southward ScanDisk utility, the FAT is non immune to grow beyond 4,177,920 clusters, placing the volume limit at 124.55 GB. The open FAT + specification proposes how to store larger files upwards to 256 GB on slightly modified and otherwise backwards uniform FAT32 volumes, but imposes a gamble that disk tools or FAT32 implementations not aware of this extension may truncate or delete files exceeding the normal FAT32 file size limit.

NTFS (New Technology File System)

NTFS or New Technology File System is the standard file system of Microsoft Windows NT and its descendants, Windows 2000, Windows XP, Windows 7 and Windows Servers. NTFS is a descendant of HPFS, the file organisation designed by Microsoft and IBM for Os/2 every bit a replacement for the older Fat file organization of MS-DOS. The improvements over FAT was back up for meta-data and the apply of advanced data structures in order to amend functioning, reliability, and disk space utilization. NTFS incorporates these plus boosted extensions such as security access control lists and file organisation journaling. In NTFS everything that has anything to do with a file (name, creation appointment, access permissions, and even contents) is written down as meta-data. Internally, NTFS uses binary trees in order to store the file organisation data; although complex to implement, this allows fast access times and decreases fragmentation. A file system journal is used in order to guarantee the integrity of the file system itself (but not of each individual file). Systems using NTFS are known to have improved reliability, a particularly of import requirement considering the unstable nature of the older versions of Windows NT.

NTFS has gone through an evolution of versions, starting from v.1.0 in mid-1993 with Windows NT 3.1, then v.i.1 in 1994 for NT 3.five, then v.i.two for NT4 in 1996 (some times referred to as NTFS 4.0), v.iii.0 for Windows 2000 in twelvemonth 2000 (some times referred to every bit NTFS 5.0), upward to v.three.1 for Windows XP in 2001 (some times referred to as NTFS 5.1).

The central organization structure of the NTFS file system is the master file table (MFT). NTFS keeps multiple copies of the critical portion of the MFT to protect against corruption and information loss. Like FAT and FAT32, NTFS uses clusters to store data files. All the same, the size of the clusters is non dependent on the size of the disk or partitioning. A cluster size every bit small equally 512 bytes can be specified, regardless of whether a sectionalization is 6 GB or sixty GB. Using pocket-sized clusters not just reduces the amount of wasted disk space, but too reduces file fragmentation, a condition where files are cleaved upward over many not-contiguous clusters, resulting in slower file admission. Because of its power to use small clusters, NTFS provides practiced performance on large drives. Finally, the NTFS file organisation supports hot fixing, a process through which bad sectors are automatically detected and marked so that they will not be used.

In theory, the maximum NTFS volume size is two⁶⁴− 1 clusters. Nevertheless, the maximum NTFS volume size equally implemented in Windows XP Professional is 2³²− 1 clusters partly due to segmentation table limitations. For instance, using 64 kB clusters, the maximum Windows XP NTFS volume size is 256 TBs. Using the default cluster size of 4 kB, the maximum NTFS book size is 16 TB. Because partition tables on master kicking tape (MBR) disks only support division sizes up to 2 TB, dynamic volumes must exist used to create NTFS volumes over 2 TB. Equally designed, the maximum NTFS file size is xvi EB (16 × 1024⁶ or ii⁶⁴ bytes). Equally implemented, the maximum NTFS file size is 16 TB. With Windows 8, the maximum NTFS file size is 256 TB.

Ext2/3/4

The ext2 or second extended file organisation was the standard file system used on the Linux operating system for a number of years and remains in broad utilize. It was initially designed by Remy Card based on concepts from the extended file system. It is quite fast, enough so that it is used as the standard confronting which to mensurate many benchmarks. Its main drawback is that it is non a journaling file system. The Ext2 file arrangement supports a maximum disk or partition size of 4 terabytes. Its successor, Ext3, has a journal and is compatible with Ext2.

The ext3 or third extended file organization is a journaled file system that is coming into increasing apply among users of the Linux operating organization. Although its performance and scalability are less bonny than those of many of its competitors such as ReiserFS and XFS, information technology does have the pregnant reward that users can upgrade from the pop Ext2 file system without having to back up and restore data. The ext3 file system adds a journal without which the file organisation is a valid Ext2 file system. An Ext3 file arrangement tin exist mounted and used every bit an Ext2 file arrangement. All of the file system maintenance utilities for maintaining and repairing the Ext2 file arrangement can as well be used with the Ext3 file system, which means Ext3 has a much more mature and well-tested gear up of maintenance utilities bachelor than its rivals.

The ext4 is the fourth extended, journaling, file system for Linux, developed equally the successor to ext3. The periodical allows the file system to quickly return to a consistent state afterward an unscheduled system shutdown acquired by a ability outage or a system crash. This feature greatly reduces the risk of file system abuse (and the need for lengthy file system checks). ReiserFS too handles directories containing huge numbers of pocket-size files very efficiently. Unfortunately, converting a system to ReiserFS requires users of Ext2 to completely reformat their disks, which is a disadvantage not shared by its main competitor Ext3. Considering of its advantages many Linux distributions have made information technology the default file organisation.

The ext4 file organization can support volumes with sizes up to i Exabyte (EB) (1,000 Terabytes = 10¹⁸ Bytes) and files with sizes up to 16 Terabytes (TB). Ext4 is backward uniform with ext3 and ext2, making it possible to mount ext3 and ext2 as ext4. Ext3 is partially frontwards compatible with ext4.

Ext4 does non yet have as much support equally ext2 and ext3 on not-Linux operating systems.

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