Volume Topology

Topology of Local Volume Replicas

The primary copies for containers of local volumes are placed on the local node. The nodes for the replica copies for containers of local volumes are chosen in the following order:

1. Use a topology that is explicitly specified for replicas during volume creation or modification.
2. Use the relative path for replicas of local volumes if the configuration parameter specifies such a path.
3. Use the default volume topology.

See Setting the Topology for Local Volume Replicas, Creating Replicas of Local Volumes in Custom Topology Using the CLI, and Setting Default Volume Topology Using the CLI.

Mirror Volume Topology

When the root volume on a cluster is mirrored, the source root volume contains a writable volume link, .rw that points to the read/write copies of all local volumes. In that case, the mount path / refers to one of the root volume's mirrors, and is read-only. The mount path /.rw refers to the source volume, and is read/write.

A mount path that consists entirely of mirrored volumes refers to a mirrored copy of the specified volume. When a mount path contains volumes that are not mirrored, the path refers to the target volume directly. In cases where a path refers to a mirrored copy, the .rw link is useful for navigating to the read/write source volume.

Sample Volume Topology with Mirrors

The following example shows a volume topology with mirrors:

For the four volumes /, a, b, and c, the following table indicates the volumes referred to by example mount paths for particular combinations of mirrored and not mirrored volumes in the path: