What file system does CentOS use by default?

CentOS uses the XFS file system by default. XFS is a very good journaling file system; it has various improvements that make it stand out in the list of file system groups, such as logging for metadata operations, scalable/parallel I/O, suspend/resume I/O, online defragmentation, delayed performance allocation.

#The operating environment of this tutorial: centos7 system, thinkpad t480 computer.

CentOS is a free, open source, and redistributable open source operating system. CentOS (Community Enterprise Operating System, Chinese meaning community enterprise operating system) is one of the Linux distributions.

CentOS Linux distribution is a stable, predictable, manageable and reproducible platform derived from Red Hat Enterprise Linux (RHEL) in accordance with open source code (mostly GPL open source license) Compiled from the source code specified for release.

CentOS uses the XFS file system by default.

XFS

XFS is a very excellent log file system designed by SGI. XFS comes with various improvements that enable it to stand out in the file system crowd list, such as logging for metadata operations, scalable/parallel I/O, suspend/resume I/O, online defragmentation, delayed performance allocation , etc.

About 2002, XFS was incorporated into the Linux kernel. In 2009, RHEL Linux version 5.4 used the XFS file system. Due to its high performance, architectural scalability and robustness, XFS has been the first choice for many enterprise systems, especially those with large amounts of data. Now, RHEL/CentOS 7 and Oracle Linux use XFS as their default file system.

Disadvantages: The XFS file system cannot be shrunk, and performance will decrease when a large number of files are deleted.

Why does CENTOS 7.0 start to choose XFS as the default file system?

The commercial version of Red Hat decided to use xfs as the default, so the community version of centos naturally has to keep up.

The main features include the following points

• Data integrity:

  Using the XFS file system, when unexpected downtime occurs, first of all, because the file system has enabled the log function, the files on your disk will no longer be unexpectedly down. The opportunity was destroyed. No matter how many files and data are currently stored in the file system, the file system can quickly restore the disk file contents in a very short time based on the recorded logs.

• Transmission characteristics:

  The XFS file system adopts an optimization algorithm, and logging has very little impact on the overall file operation. XFS queries and allocates storage space very quickly. The xfs file system can continuously provide fast response times. The author has tested XFS, JFS, Ext3, and ReiserFS file systems, and the performance of the XFS file system is quite outstanding.

• Scalability:

  XFS is a full 64-bit file system that can support millions of T bytes of storage space. The support for both extra-large files and small-sized files is outstanding, and it supports an extremely large number of directories. The maximum supported file size is 263 = 9 x 1018 = 9 exabytes, and the maximum file system size is 18 exabytes.

  XFS uses a tall table structure (B-tree) to ensure that the file system can quickly search and allocate space quickly. XFS can continuously provide high-speed operations, and the performance of the file system is not limited by the number of directories and files in the directory.

• Transmission bandwidth:

  XFS can store data with performance close to raw device I/O. In the test of a single file system, its throughput can reach up to 7GB per second, and for read and write operations on a single file, its throughput can reach 4GB per second.

The difference between xfs and ext4:

Difference 1: The size of a single file

EXT4 can be 16GB to 16TB, And XFS can be 16TB to 16EB.

Difference 2: The maximum file system size

EXT4 can be 1EB, while XFS can be 8EB.

Difference three:

EXT4 is limited by disk structure and compatibility issues, and its scalability and scalability are not as good as XFS.

Note:

Due to the historical disk structure, Ext4's inode number limit (32 digits) can only have a maximum of about 4 billion files. Moreover, the maximum single file size of Ext4 can only support 16T (4K block size), which is currently a bottleneck. XFS uses 64-bit management space, and the file system size can reach the EB level.

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