What is the difference between xfs and ext4 in linux

Differences: 1. The size of a single file, EXT4 can be 16GB to 16TB, while XFS can be 16TB to 16EB; 2. The maximum file system size, EXT4 can be 1EB, while XFS is 8EB; 3. EXT4 Limited by disk structure and compatibility issues, scalability and scalability are not as good as XFS.

#The operating environment of this tutorial: CentOS 6 system, Dell G3 computer.

The default file system starting from centos7.0 is xfs, centos6 is ext4, and centos5 is ext3.

EXT4

Ext4 is the abbreviation of the fourth generation extended file system, which was launched in 2008. It's a really solid file system, it's been the default option in almost most distributions over the past few years, and it's built from older code. It is a journaling file system, which means that it records the location of files on the disk and any other changes to the disk. If the system crashes, thanks to journal technology, the file system is rarely damaged.

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.

The difference between xfs and ext4:

Difference 1: The size of a single file

EXT4 can be 16GB to 16TB, while 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.

Performance test

Tested the performance of 4k random read and write, direct=1, numjobs=20, iodepth=128

Disk information

Disk /dev/sdc1: 4000.8 GB, 4000785104896 bytes, 7814033408 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes

Test data

##File system 4k-randread 4k-read 4k -randwrite 4k-write XFS iops=426 iops=42773 iops=313 iops=24732 EXT4 iops=430 iops=41636 iops=315 iops=19095 ##There is basically no difference in IOPS at the level of 4k. 4k random writing to XFS is slightly better than EXT4 .

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