XFS in Linux Server Operating System Log Files

Article Title: XFS System in the Linux server operating system log file. Linux is a technology channel of the IT lab in China. Including desktop applications, Linux system management, kernel research, embedded systems, open source, and other basic categories. XFS is a high-performance 64-bit file system, developed by SGI to replace the original EFS file system. XFS maintains cache consistency, locates data, and distributes disk requests to provide low-latency and high-bandwidth access to file system data. Currently, SGI has transplanted the XFS file system from IRIX to Linux.
Allocation groups)
When creating an XFS file system, the underlying Block devices are divided into eight or more linear regions of equal size (region). You can think of them as chunks) or "linear range". In XFS, each region is called an "allocation group ". The allocation group is unique because each allocation Group manages its own inode and free space. In fact, these allocation groups are converted into a file subsystem, these subsystems are transparently stored in the XFS file system. With an allocation group, XFS Code allows multiple threads and processes to run in parallel, even if many of them are performing large-scale IO operations on the same file system. Therefore, the combination of XFS with some high-end hardware will achieve high performance without making the file system a bottleneck. The allocation group uses an efficient B + tree internally to track the main data, with superior performance and great scalability.
Log records
XFS is also a log recording file system that allows quick recovery after unexpected reboot. Like ReiserFS, XFS uses logical logs. Unlike ext3, XFS records text file system blocks to logs, but uses an efficient disk format to record metadata changes. In terms of XFS, logical logging is very suitable. on high-end hardware, logs are often the most popular Resources in the entire file system. By using space-saving logical log records, you can minimize the contention for logs. In addition, XFS allows logs to be stored on another block device, for example, one partition on another disk. This feature is useful and further improves the performance of the XFS file system.
Delay allocation
Latency allocation is a unique feature of XFS. It is used to find free space areas and store new data. Through latency allocation, XFS has won many opportunities to optimize write performance. When writing data to a disk, XFS can intelligently allocate free space in this way to optimize the file system performance. In particular, to add a batch of new data to a single file, XFS can allocate a single, adjacent area on the disk to store the data. If XFS does not delay its allocation, it may have unknowingly written data to multiple non-adjacent blocks, significantly reducing the write performance. However, because XFS delays the allocation decision, it can write data at once, thus improving the write performance and reducing the fragmentation of the entire file system. Latency allocation also has another advantage in terms of performance. To create many "short-lived" temporary files, XFS may not need to write all these files to the disk at all. Because these files have never been assigned any blocks, you do not have to release any blocks or even touch the underlying File System metadata.