Rebalancing volumes in computer system comprising upper and lower cluster

1. A computer system comprising an upper cluster and a lower cluster, wherein

the upper cluster has a plurality of first nodes, and stores a management-subject data unit redundantly in a plurality of volumes managed by a plurality of first nodes,

the lower cluster has a plurality of second nodes, and provides a plurality of the volumes on a basis of storage regions of storage apparatuses of the second nodes,

a processor of the computer system performs control such that a plurality of the volumes storing the data unit in the upper cluster for redundancy are not volumes based on a storage region of a storage apparatus of one second node,

the processor of the computer system

identifies a second node having a storage region on which each of a plurality of the volumes storing the data unit for redundancy is based, and

in a case where one second node is identified for a plurality of the volumes, moves some volumes that are included in a plurality of the volumes and are based on a storage region of the one identified second node to a second node other than the one identified second node.

2. The computer system according to claim 1 , wherein

the processor of the computer system performs control such that all of a plurality of the volumes storing the data unit for redundancy are volumes based on storage regions of storage apparatuses of different second nodes.

3. The computer system according to claim 2 , wherein

the redundancy is attained by multiplication of the data unit.

4. The computer system according to claim 2 , wherein

the redundancy is attained by erasure coding.

5. The computer system according to claim 1 , further comprising a managing apparatus, wherein

a processor of the managing apparatus

identifies a second node having a storage region on which each of a plurality of the volumes storing the data unit for redundancy is based, and

in a case where one second node is identified for a plurality of volumes, instructs a processor of a second node in the lower cluster to move some volumes that are included in a plurality of the volumes and are based on a storage region of the one identified second node to a second node other than the one identified second node.

6. The computer system according to claim 1 , further comprising a managing apparatus, wherein

a processor of the managing apparatus transmits, to the lower cluster, redundancy volume information that can identify a plurality of the volumes storing the data unit for redundancy, and

a processor of a second node in the lower cluster

receives the redundancy volume information,

identifies a second node having a storage region on which each of a plurality of the volumes corresponding to the redundancy volume information is based, and

in a case where one second node is identified for a plurality of volumes, moves some volumes that are in a plurality of the volumes and are based on a storage region of the one identified second node to a second node other than the one identified second node.

7. The computer system according to claim 2 , wherein

the processor of the computer system

receives redundancy volume plurality of the volumes storing the data unit for redundancy, and

generates a plurality of volumes corresponding to the redundancy volume information such that the generated plurality of volumes are volumes based on storage regions of storage apparatuses of different second nodes.

8. A volume arrangement managing apparatus that manages movement of volumes in a computer system including an upper cluster and a lower cluster, wherein

the upper cluster has a plurality of first nodes, and stores a management-subject data unit redundantly in a plurality of volumes managed by a plurality of first nodes,

the lower cluster has a plurality of second nodes, and provides a plurality of the volumes on a basis of storage regions of storage apparatuses of the second nodes,

a processor of the managing apparatus performs control such that a plurality of the volumes storing the data unit in the upper cluster for redundancy are not volumes based on a storage region of a storage apparatus of one second node,

the processor of managing apparatus

identifies a second node having a storage region on which each of a plurality of the volumes storing the data unit for redundancy is based, and

in a case where one second node is identified for a plurality of the volumes, moves some volumes that are included in a plurality of the volumes and are based on a storage region of the one identified second node to a second node other than the one identified second node.

9. A volume arrangement management method performed by a computer system including an upper cluster and a lower cluster, the method comprising:

storing, by the upper cluster having a plurality of first nodes, a management-subject data unit redundantly in a plurality of volumes managed by a plurality of first nodes;

providing, by the lower cluster having a plurality of second nodes, a plurality of the volumes on a basis of storage regions of storage apparatuses of the second nodes;

performing control, by the computer system, such that a plurality of the volumes storing the data unit in the upper cluster for redundancy are not volumes based on a storage region of a storage apparatus of one second node;

identifying by the computer system a second node having a storage region on which each of a plurality of the volumes storing the data unit for redundancy is based, and

in a case where one second node is identified for a plurality of the volumes, moving by the computer system some volumes that are included in a plurality of the volumes and are based on a storage region of the one identified second node to a second node other than the one identified second node.