Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Figure 14-1
Example of a two-site remote mirror configuration
Cluster
nodes
Disk enclosures Disk enclosures
Site A
Private network
Site B
Fibre Channel
switch
Fibre Channel
switch
Metropolitan or
wide area
network link
(Fibre Channel
or DWDM)
Cluster
nodes
If a disk group is configured across the storage at the sites, and inter-site
communication is disrupted, there is a possibility of a serial split brain condition
arising if each site continues to update the local disk group configuration copies.
See “Handling conflicting configuration copies” on page 243.
VxVM provides mechanisms for dealing with the serial split brain condition,
monitoring the health of a remote mirror, and testing the robustness of the cluster
against various types of failure (also known as fire drill).
For applications and services to function correctly at a site when other sites have
become inaccessible, at least one complete plex of each volume must be configured
at each site (site-based allocation), and the consistency of the data in the plexes
at each site must be ensured (site consistency).
By tagging disks with site names, storage can be allocated from the correct location
when creating, resizing or relocating a volume, and when changing a volume’s
layout.
As shown in the examples, the network connectivity can be Fibre Channel (FC) or
Dense Wavelength Division Multiplex (DWDM). The storage network and the
heartbeat network can be the same network.
Administering sites and remote mirrors
About sites and remote mirrors
466