xfs_info - display XFS filesystem geometry information
xfs_info [ -t mtab ] [ mount-point | block-device | file-image ]
xfs_info -V
xfs_info displays geometry information about an existing XFS filesystem. The mount-point argument is the pathname of a directory where the filesystem is mounted. The block-device or file-image contain a raw XFS filesystem. The existing contents of the filesystem are undisturbed.
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. This option has no effect with the block-device or file-image parameters.
Prints the version number and exits. The mount-point argument is not required with -V.
Understanding xfs_info output.
Suppose one has the following "xfs_info /dev/sda" output:
meta-data=/dev/pmem0 isize=512 agcount=8, agsize=5974144 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=1, sparse=1, rmapbt=1 = reflink=1 data = bsize=4096 blocks=47793152, imaxpct=25 = sunit=32 swidth=128 blks naming =version 2 bsize=4096 ascii-ci=0, ftype=1 log =internal log bsize=4096 blocks=23336, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0
Here, the data section of the output indicates "bsize=4096", meaning the data block size for this filesystem is 4096 bytes. This section also shows "sunit=32 swidth=128 blks", which means the stripe unit is 32*4096 bytes = 128 kibibytes and the stripe width is 128*4096 bytes = 512 kibibytes. A single stripe of this filesystem therefore consists of four stripe units (128 blocks / 32 blocks per unit).