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xfs(5) [debian man page]

xfs(5)								File Formats Manual							    xfs(5)

xfs - layout of the XFS filesystem DESCRIPTION
An XFS filesystem can reside on a regular disk partition or on a logical volume. An XFS filesystem has up to three parts: a data section, a log section, and a realtime section. Using the default mkfs.xfs(8) options, the realtime section is absent, and the log area is con- tained within the data section. The log section can be either separate from the data section or contained within it. The filesystem sec- tions are divided into a certain number of blocks, whose size is specified at mkfs.xfs(8) time with the -b option. The data section contains all the filesystem metadata (inodes, directories, indirect blocks) as well as the user file data for ordinary (non-realtime) files and the log area if the log is internal to the data section. The data section is divided into a number of allocation groups. The number and size of the allocation groups are chosen by mkfs.xfs(8) so that there is normally a small number of equal-sized groups. The number of allocation groups controls the amount of parallelism available in file and block allocation. It should be increased from the default if there is sufficient memory and a lot of allocation activity. The number of allocation groups should not be set very high, since this can cause large amounts of CPU time to be used by the filesystem, especially when the filesystem is nearly full. More allocation groups are added (of the original size) when xfs_growfs(8) is run. The log section (or area, if it is internal to the data section) is used to store changes to filesystem metadata while the filesystem is running until those changes are made to the data section. It is written sequentially during normal operation and read only during mount. When mounting a filesystem after a crash, the log is read to complete operations that were in progress at the time of the crash. The realtime section is used to store the data of realtime files. These files had an attribute bit set through xfsctl(3) after file cre- ation, before any data was written to the file. The realtime section is divided into a number of extents of fixed size (specified at mkfs.xfs(8) time). Each file in the realtime section has an extent size that is a multiple of the realtime section extent size. Each allocation group contains several data structures. The first sector contains the superblock. For allocation groups after the first, the superblock is just a copy and is not updated after mkfs.xfs(8). The next three sectors contain information for block and inode alloca- tion within the allocation group. Also contained within each allocation group are data structures to locate free blocks and inodes; these are located through the header structures. Each XFS filesystem is labeled with a Universal Unique Identifier (UUID). The UUID is stored in every allocation group header and is used to help distinguish one XFS filesystem from another, therefore you should avoid using dd(1) or other block-by-block copying programs to copy XFS filesystems. If two XFS filesystems on the same machine have the same UUID, xfsdump(8) may become confused when doing incremental and resumed dumps. xfsdump(8) and xfsrestore(8) are recommended for making copies of XFS filesystems. OPERATIONS
Some functionality specific to the XFS filesystem is accessible to applications through the xfsctl(3) and by-handle (see open_by_handle(3)) interfaces. MOUNT OPTIONS
Refer to the mount(8) manual entry for descriptions of the individual XFS mount options. SEE ALSO
xfsctl(3), mount(8), mkfs.xfs(8), xfs_info(8), xfs_admin(8), xfsdump(8), xfsrestore(8). xfs(5)

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xfs_growfs(8)						      System Manager's Manual						     xfs_growfs(8)

xfs_growfs, xfs_info - expand an XFS filesystem SYNOPSIS
xfs_growfs [ -dilnrxV ] [ -D size ] [ -e rtextsize ] [ -L size ] [ -m maxpct ] [ -t mtab ] [ -R size ] mount-point xfs_info [ -t mtab ] mount-point DESCRIPTION
xfs_growfs expands an existing XFS filesystem (see xfs(5)). The mount-point argument is the pathname of the directory where the filesystem is mounted. The filesystem must be mounted to be grown (see mount(8)). The existing contents of the filesystem are undisturbed, and the added space becomes available for additional file storage. xfs_info is equivalent to invoking xfs_growfs with the -n option (see discussion below). OPTIONS
-d | -D size Specifies that the data section of the filesystem should be grown. If the -D size option is given, the data section is grown to that size, otherwise the data section is grown to the largest size possible with the -d option. The size is expressed in filesystem blocks. -e Allows the real-time extent size to be specified. In mkfs.xfs(8) this is specified with -r extsize=nnnn. -i The new log is an internal log (inside the data section). [NOTE: This option is not implemented] -l | -L size Specifies that the log section of the filesystem should be grown, shrunk, or moved. If the -L size option is given, the log section is changed to be that size, if possible. The size is expressed in filesystem blocks. The size of an internal log must be smaller than the size of an allocation group (this value is printed at mkfs(8) time). If neither -i nor -x is given with -l, the log contin- ues to be internal or external as it was before. [NOTE: These options are not implemented] -m Specify a new value for the maximum percentage of space in the filesystem that can be allocated as inodes. In mkfs.xfs(8) this is specified with -i maxpct=nn. -n Specifies that no change to the filesystem is to be made. The filesystem geometry is printed, and argument checking is performed, but no growth occurs. -r | -R size Specifies that the real-time section of the filesystem should be grown. If the -R size option is given, the real-time section is grown to that size, otherwise the real-time section is grown to the largest size possible with the -r option. The size is expressed in filesystem blocks. The filesystem does not need to have contained a real-time section before the xfs_growfs operation. -t Specifies an alternate mount table file (default is /proc/mounts if it exists, else /etc/mtab). This is used when working with filesystems mounted without writing to /etc/mtab file - refer to mount(8) for further details. -V Prints the version number and exits. The mount-point argument is not required with -V. xfs_growfs is most often used in conjunction with logical volumes (see md(4) and lvm(8) on Linux). However, it can also be used on a regu- lar disk partition, for example if a partition has been enlarged while retaining the same starting block. PRACTICAL USE
Filesystems normally occupy all of the space on the device where they reside. In order to grow a filesystem, it is necessary to provide added space for it to occupy. Therefore there must be at least one spare new disk partition available. Adding the space is often done through the use of a logical volume manager. SEE ALSO
mkfs.xfs(8), md(4), lvm(8), mount(8). xfs_growfs(8)
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