DOKK / manpages / debian 12 / xfsprogs / xfs_rtcp.8.en
xfs_rtcp(8) System Manager's Manual xfs_rtcp(8)

xfs_rtcp - XFS realtime copy command

xfs_rtcp [ -e extsize ] [ -p ] source ... target
xfs_rtcp -V

xfs_rtcp copies a file to the realtime partition on an XFS filesystem. If there is more than one source and target, the final argument (the target) must be a directory which already exists.

Sets the extent size of the destination realtime file.
Use if the size of the source file is not an even multiple of the block size of the destination filesystem. When -p is specified xfs_rtcp will pad the destination file to a size which is an even multiple of the filesystem block size. This is necessary since the realtime file is created using direct I/O and the minimum I/O is the filesystem block size.
Prints the version number and exits.

xfs(5), mkfs.xfs(8), mount(8).

Currently, realtime partitions are not supported under the Linux version of XFS, and use of a realtime partition WILL CAUSE CORRUPTION on the data partition. As such, this command is made available for curious DEVELOPERS ONLY at this point in time.