Atitit. ntfs & #160; ext & #160; comparison of new file system features, atitit. ntfsext

Comparison of new features of atitit. ntfs ext file system, atitit. ntfsext

Comparison of new features of atitit. ntfs ext File System

 

 

1. Features of Modern File Systems 2

1.1. Restore Log2

1.2. Compression 2

1.3. Meta ext2

1.4. Full text of Fulltext shortsearch 2

1.5. Copy verification 2

1.6. sparse files, a feature of file systems such as UNIX and NTFS. 2

2. Ext2 feature 3

2.1. EXT2 second generation extension File System (English: second extended filesystem, abbreviated as ext2) 3

3. Ext3 Feature 4

3.1. · log 4

3.2. Data Integrity 4

4. Edit features of ext4 File System 4

4.1.1. Larger file systems and larger files 4

4.1.2. More subdirectories 4

4.1.3. More blocks and I-node quantity 5

4.1.4. Multi-block allocation 5

4.1.5. Persistence pre-allocation 5

4.1.6. latency allocation 5

4.1.7. Disk structure 5

4.1.8. New I-node structure 5

4.1.9. Log verification function 6

4.1.10. Support for "no log" mode 6

4.1.11. Barrier6 is enabled by default.

4.1.12. Online fragment 6

4.1.13. Support for fast fsck6

4.1.14. Support for nanosecond-level timestamp 6

5. Planned ext features 7

5.1.1. Reverse deletion 7

5.1.2. logs do not contain checksum 7

6. Ntfs features 7

6.1. Support for metadata 7

6.2. Cross-file storage, storing files (volumes) on multiple hard disks 8

6.3. Supported Disk Quota 8

6.4. NTFS has five officially released versions: v3.1 from Windows XP (2001, sometimes referred to as "NTFS 5.1") 8

7. Ext and ntfs comparison 9

8. Ref9

 

1. modern file system features 1.1. restore Log1.2. compress 1.3. meta ext1.4. Fulltext shortsearch full text 1.5. copy verification 1.6. sparse files are a feature of file systems such as UNIX and NTFS.

At the beginning, a sparse file does not contain user data and is not allocated to the disk space used to store user data. When data is written to a sparse file, NTFS gradually allocates disk space for it.

If the free space is occupied by the NULL characters of the ASCII code and the space is quite large, this file is called a sparse file and does not allocate disk blocks.

In this case, a problem occurs. The file has been created, but the disk space is not allocated. The disk block is allocated only when real data is inserted, if the file system is full, write operations on the file will fail. To prevent this situation, there are two ways: do not generate sparse files or leave sufficient space for sparse files.

In computer science, sparse files are a file storage method in a file system. When creating a file, the continuous storage space required for the file is allocated in advance, most of the files in the bucket are not filled with data. Currently, many file systems support sparse files, including most Unix and NTFS files.

Sparse files are widely used in Disk Images, database snapshots, log files, and other scientific applications.

Author: nickname: old wow's paw (full name: Attilax Akbar Al Rapanui Attila Akba Arla Panui) Name: AI long, EMAIL: 1466519819@qq.com

Reprinted please indicate Source: http://www.cnblogs.com/attilax/

 

2. Ext2 features

 

2.1. EXT2 second generation extension File System (English: second extended filesystem, abbreviated as ext2)

Is the file system used by the Linux kernel. It was designed by Rémy Card to replace ext and was added to the linux core support in January 1993. The typical ext2 implementation is the ext2fs file system driver in the Linux kernel. It supports a file system of up to 2 TB,

1. When creating an Ext2 file system, the system administrator can select the optimal Block Size (from 1024B--4096B) based on the average length of the expected file ). For example, when the average length of a file is less than several thousand characters, the block size of B is the best, this results in a small amount of internal fragments-that is, the file length does not match the disk partition of the storage block. On the other hand, large blocks are usually suitable for files larger than several thousands of bytes, because such disks transmit less, thus reducing the system overhead [1].

2. When creating an Ext2 file system, the system administrator can select the number of index nodes allocated to the partition based on the expected number of files stored in the given partition size. This effectively exploits the disk space.

3. The file system divides disk blocks into groups. Each group contains data blocks and index nodes stored on adjacent channels. This structure enables parallel access to files stored in a separate block group with less average disk seek time.

4. Before the disk data blocks are actually used, the file system pre-allocates these blocks to common files. Therefore, when the file size increases, several adjacent physical blocks are retained, which reduces the file fragmentation.

5. Quick symbolic links are supported. If a symbolic link represents a short path name (less than or equal to 60 characters), it is stored in the index node instead of being converted by a data block.

1. careful implementation of file update policies minimizes the impact of system crashes. Here is only one example to demonstrate this advantage: for example, when creating a hard link for a file, first add the hard link counter in the disk index node, then add the new name to the appropriate directory. In this way, if a hardware fault occurs before the directory is changed after the index node is updated, the directory is consistent even if the index node's counting machine produces an error. Therefore, although the data block of the file cannot be automatically recovered when the file is deleted, it does not cause disastrous consequences.

2. automatic consistency check on the file system status is supported at startup. This check is performed by the external program e2fsck,

 

3. Ext3 features

Ext3 file systems include:

3.1 .. · log

· Tree-based directory indexes are provided across multiple blocks

· Online system growth

If not, the ext3 file system is also a valid ext2 file system. In this way, well-tested and mature file system tools can be used to manage and repair ext2 file system tools without large changes. The ext2 and ext3 file systems share the same tool set, e2fsprogs with The fsck tool. This close connection also makes it easy to switch between two file systems, including upgrading to ext3 and downgrading to ext2.

3.2. Data Integrity 4. ext4 file system features edit 4.0.1. Larger file system and larger file

The Ext3 file system supports a maximum of 32 TB file systems and 2 TB files. Based on the specific architecture and system settings, the actual capacity limit may be lower than this number, that is, it can only accommodate 2 TB of file systems and 16 GB of files. The file system capacity of Ext4 reaches 1 EB, and the file capacity reaches 16 TB, which is a very large number. This may not be important for general desktops and servers, but it is important for users of large disk arrays.

4.0.2. More subdirectories

Ext3 currently only supports 32000 sub-directories, and Ext4 removes this restriction. In theory, it supports an unlimited number of sub-directories.

4.0.3. More blocks and I-nodes

The Ext3 file system uses 32-bit space to record the number of blocks and the number of I-nodes, while the Ext4 file system expands them to 64-bit.

4.0.4. Multi-block allocation

When data is written to the Ext3 file system, the Ext3 data block distributor can allocate only one 4 kb block at a time. If you write a 25600 MB file, you need to call the data block distributor, the Multiblock Allocator (MBAlloc) Multi-block Allocator of Ext4 supports allocating multiple data blocks at a time.

4.0.5. Persistence pre-allocation

If an application needs to allocate disk space before it is actually used, most file systems allocate space by writing 0 to unused disk space, such as P2P software. To ensure that the downloaded files have sufficient space for storage, an empty file with the same size as the downloaded files is often created in advance to avoid downloading failure due to insufficient disk space in the next several hours or days. Ext4 achieves persistent pre-distribution at the file system level and provides corresponding APIs, which is more efficient than the application software.

4.0.6. Delay allocation

The data block allocation policy of Ext3 is to allocate as soon as possible, while the policy of Ext4 is to delay the allocation as much as possible until the file is written in the buffer, in this way, the data block allocation of the entire file can be optimized, significantly improving the performance.

4.0.7. Disk Structure

The Ext3 file system uses indirect ing addresses. When operating large files, the efficiency is extremely low. For example, for a 25600 MB file, you need to create a ing table of data blocks in Ext3 (taking each data block size as 4 kb). Ext4 introduces the disk partition concept, each disk area is a set of continuous data blocks. The above files can be expressed as "the file data is stored in the next 25600 data blocks" by means of a disk area, which improves access efficiency.

4.0.8. New I-node Structure

Ext4 supports larger I-nodes. The default I-node size of the previous Ext3 is 128 bytes. To accommodate more extended attributes in the I-node, the default I-node size is 256 bytes. In addition, Ext4 supports quick extension of attributes and I-node retention.

4.0.9. Log Verification

Logs are the most common structure in the file system, and logs are easily damaged. Restoring data from damaged logs will cause more data corruption. Ext4 adds the verification function to log data. The log verification function can easily determine whether log data is damaged. In addition, Ext4 combines the two-phase Log Mechanism of Ext3 into one phase, improving the performance while increasing security [1].

4.0.10. Support for "no log" Mode

Logs occupy some expenses. Ext4 allows you to disable logs so that users with special requirements can improve performance.

4.0.11. Barrier is enabled by default.

The disk is equipped with an internal cache to re-adjust the write operation sequence of batch data and optimize the write performance. Therefore, the file system must write the log data to the disk before writing the Commit record. If the Commit record is written first, and the log may be damaged, data integrity will be affected. The Ext4 file system enables Barrier by default. Only when all the data before the Barrier is written to the disk can the data after the Barrier is written.

4.0.12. Online Fragment

Although the delayed allocation, multi-block allocation, and disk partition functions can effectively reduce file fragments, fragments are inevitable. Ext4 supports online fragment and provides the e4defrag tool for fragment of individual files or the entire file system.

4.0.13. Fast fsck supported

In earlier versions, fsck execution was slow because it had to check all I-nodes, ext4 adds a list of unused I-nodes to the I-node table of each block group, therefore, the Ext4 file system can skip the consistency check and only check which I-nodes are in use, thus improving the speed.

4.0.14. Support for nanosecond-level timestamps

The timestamp of the extended file system before Ext4 is in seconds, which can cope with most settings, but with the speed and integration of the processor (multi-core processor) increasing, and Linux began to develop into other application fields, it will increase the timestamp unit to the nanosecond.

Ext4 adds two bits to the time range so that the time life is prolonged by 500. The date supported by the Ext4 timestamp is increased to April 25, 2514, and Ext3 is only supported by January 18, 2038.

 

5. Planned ext features

Logical Deletion

Transparent processing of compressed and encrypted files

The undelete option allows users to easily restore previously deleted file content when necessary.

The most prominent feature missing in Log Recovery Ext2 is log, which is a required feature of a high-availability server.

Logs prevent the file system from automatically performing time-consuming checks when it is suddenly uninstalled (for example, as a consequence of system crash.

Although ext3 lacks some features of contemporary file systems, such as dynamic inode and tree-like data storage and storage structures, ext3 is regarded as one of the shortcomings of ext3.

5.0.1. Reverse Deletion

Unlike ext2, ext3 clears the block index of the file node (inode) When deleting the file. In this way, you can reduce the access to the file system when replaying logs after unclean is loaded to the file system. But it also increases the difficulty of deleting files.

Ext3 does not support transparent compression (Ext2 is supported by unofficial patches ).

5.0.2. The log does not contain a Checksum. 6. Ntfs feature 6.1. Metadata is supported.

NTFS has made several improvements to FAT and HPFS. For example, it supports metadata and uses an advanced data structure to improve performance, reliability, and disk space utilization, it also provides several additional extensions.

6.2. cross-file storage: stores files (volumes) on multiple hard disks 6.3. 6.4 disk quota is supported. NTFS has five officially released versions: v3.1 from Windows XP (2001, sometimes called "NTFS 5.1 ")

 

For example, a large company's database may have to go across different hard disks.

 

NTFS has five officially released versions:

V1.0, released with NT 3.1 and released in the middle of 1993

V1.1, released with NT 3.5 and released in autumn 1994

V1.2, provided by NT 3.51 (1995) and NT 4 (1996) (sometimes referred to as "NTFS 4.0" because the operating system version is 4.0)

V3.0 is from Windows 2000 (sometimes called "NTFS 5.0 ")

V3.1 from Windows XP (2001, sometimes referred to as "NTFS 5.1"), Windows Server 2003 (spring 2003, sometimes referred to as "NTFS 5.2"), Windows Vista (mid-2005, it is sometimes called "NTFS 6.0"), Windows Server 2008 (early 2008), Windows Server 2008 R2 (sometimes called "NTFS 6.1"), and Windows 7.

V1.0 is incompatible with V1.1 and all later versions. That is to say, the volume written with NT 3.5x cannot be read by NT 3.1 Unless NT 3.1 is updated with an NT 3.5x disc, and added support for long file names for the FAT system. V1.2 supports the security of compressed files, celebrities, and ACL-based access control lists.

V3.0 supports disk quota, encryption, sparse files, reresolution points, update serial number (USN) logs, $ Extend folders, and files in them, and improves the security descriptor, this allows you to share one security descriptor with multiple files with the same security settings.

V3.1 the master file table (MFT) item is extended using redundant MFT records (used to recover damaged MFT files.

Windows Vista provides transaction NTFS, NTFS symbolic links, Volume shrinking, and self-recovery features, but these additional features are provided by the operating system rather than the features of the file system itself.

The recovery capability designed in the NTFS file system does not require you to run the disk repair program in the NTFS Volume. In a system crash event, the NTFS file system uses the log file and review point information to automatically restore the consistency of the file system.

(6) The B-Tree structure of the NTFS folder allows users to access files in a large folder at a faster speed than those in a folder with smaller volumes.

) Can be used to compress a single file and folder in an NTFS Volume. The NTFS system's compression mechanism allows users to directly read and write compressed files without using the decompression software to expand these files.

7. Ext and ntfs comparison

The ext file system supports link (hard or soft chain, refer to the ln command). It does not produce much fragments as quickly as ntfs does; supports more types of files (such as device files under/dev, virtual files under/proc, socket files, etc.). Both ext3 and ntfs are log systems, it can provide rapid/correct recovery with sudden power loss. The ext3 log removal function is ext2, which improves the efficiency of some ext and has a significant advantage.

 

 

 

8. Ref

Ext3_baidu Baike .htm

Ext4_baidu Baike .htm

Ntfs_baidu Baike .htm

Sparse file _ Baidu Baike .htm