Edward Shishkin support for selective file migration to Reiser5. Within the framework of the Reiser5 project, a variant of the ReiserFS file system that implements support for parallel scalable logical volumes at the file system level, rather than the block device level, to efficiently distribute data across a logical volume.
Previously, the migration of data blocks was carried out exclusively in the context of balancing the Reiser5 logical volume in order to maintain fair distribution on it. Now you can move the data of any file to any disk component of the logical volume. Moreover, it is possible to mark this file in a special way so that the balancing procedure will ignore it, and, consequently, its data blocks will remain on the specified disk.
Published user interface for migration and file tagging. This interface assumes the use of the ioctl(2) system call and is intended for application programmers. Migration and labeling is also available to the end user using the volume.reiser4(8) utility.
As an obvious application of this functionality, you can move all "hot" (i.e., most frequently used) files to the highest performing components of the logical volume, and "pin" them there. For this purpose it is recommended to use , which does not participate in regular data distribution. You can also move files to regular drive components of a logical volume, but this may suffer "fairness"
distribution of data, which will lead to a violation .
Source: opennet.ru