The following nine kinds of group hierarchical structures, including a nonhierarchical structure, are available. However, groups that can be created in the root class are only non-nested mirror groups.
higher level group <----------------------------------------------> lower level group mirror group (*1) mirror group (*1) - stripe group (*3) mirror group (*1) - stripe group (*3) - concatenation group (*7) mirror group (*1) - concatenation group (*5) stripe group (*2) stripe group (*2) - concatenation group (*6) concatenation group (*4) concatenation group (*4) - switch group (*9) switch group (*8)
Possible operations on groups at each hierarchical level that change the structure are as follows.
(*1) The highest level mirror group
Disks, lower level stripe groups, and lower level concatenation groups can be connected or disconnected. However, disconnection is impossible if it can change the volume configuration or status.
If no volume exits, the group itself can be removed.
Volumes can be created or removed.
(*2) The highest level stripe group
If no volume exists, disks and lower level concatenation groups can be connected or disconnected.
If no volume exists, this type group can be connected to a mirror group.
If no volume exists, the group itself can be removed.
If more than one disks or lower level concatenation groups are connected to, volumes can be created or removed.
(*3) The lower level stripe group
This type group can be disconnected from the highest level mirror group. However, disconnection is impossible if it can change the volume configuration or status.
(*4) The highest level concatenation group
If no switch group is connected to, disks can be connected.
If no disk is connected to, lower level switch groups can be connected.
If no volume area exists on the disk that was connected last, that disk can be disconnected.
If no volume area exists in the group that was connected last, that lower switch group can be disconnected.
If no volume exists and if no lower level switch group is connected to, this group can be connected to a mirror group or a stripe group.
If no volume exists, the group itself can be removed.
Volumes can be created or removed.
(*5) Lower level concatenation group connected to the highest level mirror group
Disks can be connected.
If more than one disk is connected and no volume area exists on the disk that was connected last, that disk can be disconnected.
This type group can be disconnected from the highest level mirror group. However, disconnection is impossible if it can change the volume configuration or status.
(*6) Lower level concatenation group connected to the highest level stripe group
If more than one disk is connected and no volume exists within the highest level group, the disk that was connected last can be disconnected.
(*7) Lower level concatenation group connected to a lower level stripe group
None.
(*8) The highest level switch group
Disks can be connected.
If no volume or inactive disk exists, the active disk can be disconnected.
The inactive disk can be disconnected.
If no volume exists, the group itself can be removed.
Volumes can be created or removed.
(*9) Lower level switch group
Disks can be connected.
The inactive disk can be disconnected.
If no volume area exists and if this group is the switch group that was last connected to a higher level concatenation group, this group can be disconnected from that concatenation group.
