xfs_mkfile

xfs_mkfile [-n] [-l|s] [-v] size target

-n
    Do not actually create the file; just print out a summary of what would happen if the file were created.

-l
    Lock the target. The file will be locked and the allocation state is not released if creation fails, and the lock will be released on a clean exit. Lock is not supported on block device and shared file residing on a cluster file system.

-s
    Sparse the target. Only supported on regular file. Data for blocks that are all zeros are not actually written to the disk, thereby avoiding filling up the filesystem with large files containing mostly zeros.

-v
    Be verbose. Print out information about the space allocation for the file.

size
    The size of the file to create. This should be specified in bytes (with optional k, m, g, t, p suffixes representing Kilobytes, Megabytes, Gigabytes, Terabytes, Petabytes respectively).

target
    The pathname of the file or block device to be created.

The `xfs_mkfile` command efficiently pre-allocates space for a file, commonly used in creating container images, virtual machine disks, or other large files within an XFS filesystem.

Unlike simply writing to the file which can lead to fragmentation, `xfs_mkfile` uses XFS's space pre-allocation features to ensure the file is ideally laid out on disk from the beginning, improving performance when the file is later accessed. This is especially beneficial for read-intensive workloads or when the file is frequently accessed by multiple processes.

The primary advantage of `xfs_mkfile` lies in its ability to optimize file placement on the XFS filesystem, reducing fragmentation and improving I/O performance for the created file. It ensures contiguous allocation, thereby improving speed of access to large file. It writes one or more blocks to the target in a way that initializes the XFS metadata to create the file. The target may be a regular file, block device or a shared file residing on a cluster file system.

This command is XFS-specific. It will not work reliably on other filesystems. Using it on a block device will destroy any existing filesystem on that device. It is essential to use the correct size argument.

On success, it returns 0. On failure, it returns a non-zero value. The non-zero status indicates an error occurred during file creation, such as insufficient disk space, invalid arguments, or file access issues.

The `xfs_mkfile` command was introduced as part of the XFS filesystem utilities. It was designed to efficiently create large files on XFS filesystems, leveraging XFS's space pre-allocation capabilities to minimize fragmentation and improve performance. It addresses the need for a specialized tool that can optimize file layout for read-intensive applications on XFS.

mkfile(8), fallocate(1)