DM-MP is the standard OS multipath function of RHEL.
mpath devices of DM-MP can be managed in local and shared classes.
When using DM-MP, note the following points.
A device to which DM-MP is applied for the virtio block device (/dev/vdX) on the KVM guest, cloud environment (except an FJcloud-Baremetal environment), and RHOSP environment cannot be registered to GDS.
Do not use DM-MP for devices (local disks or iSCSI devices) used for the mirroring among servers. If you configure DM-MP, register these devices in the black list.
If there are multiple mpath devices in the system, registering a disk to a shared class and a local class may fail.
The number of mpath devices that registering a disk fails depends on the system processing performance. Only as a guide, it is 12,000/the number of multipaths. If the number of multipaths is 2, it is 6,000.
