Inter-disk settings for logical volume copies
The allocation of a single copy of a logical volume on disk is fairly straightforward.
When you create mirrored copies, however, the resulting allocation is somewhat complex. The figures that follow show minimum maximum and inter-disk (Range) settings for the first instance of a logical volume, along with the available Strict settings for the mirrored logical volume copies.
For example, if there are mirrored copies of the logical volume, the minimum setting causes the physical partitions containing the first instance of the logical volume to be allocated on a single physical volume, if possible. Then, depending on the setting of the Strict option, the additional copy or copies are allocated on the same or on separate physical volumes. In other words, the algorithm uses the minimum number of physical volumes possible, within the constraints imposed by other parameters such as the Strict option, to hold all the physical partitions.
Strict = y means that each copy of the logical
partition is placed on a different physical volume. The setting
= n means that the copies are not restricted to different physical
volumes. By comparison, the
Super Strict option would not
allow any physical partition from one mirror to be on the same disk as a physical
partition from another mirror of the same logical volume.
The following figure illustrates a minimum inter-disk allocation policy with differing Strict settings:
The following figure illustrates a maximum inter-disk allocation policy with differing Strict settings: