Local Mirroring
A local mirror volume is a mirror volume whose source is on the same cluster. Local mirror volumes are useful for load balancing or for providing a read-only copy of a data set.
You can locate your local mirror volumes in specific servers or on racks with particularly high bandwidth, mounted in a public directory separate from the source volume.
The most frequently
accessed volumes in a cluster are likely to be the root volume and its immediate
children. To load-balance read operations on these volumes, mirror the root
volume (typically mapr.cluster.root, which is mounted at
/). By mirroring these volumes, you can serve read requests
from the mirrors, and distribute load across the nodes. Less-frequently accessed
volumes that are lower in the hierarchy do not need mirror volumes. Since the
mount paths for those volumes are not mirrored throughout, those volumes are
writable.
/) points to the mirror volume, hence root is read-only.
For read-write copy of root (/), you must use the special path,
/.rw