The network
interfaces used must support DLPI (link level).
There must be less than 200
milliseconds of latency in the network between the data centers.
No routing is allowed for
the networks between the data centers.
Routing is allowed to the
third data center if a Quorum Server is used in that data center.
The maximum distance between
the data centers for this type of configuration is currently limited
by the maximum distance supported for the networking type or Fibre
Channel link type being used, whichever is shorter.
Currently, FDDI offers a
total ring length of 100 kilometers. This will allow up to 50 kilometers
between data centers for both two and three data center solutions.
There can be a maximum of
500 meters between the Fibre Channel hubs or switches in the two
data centers if Short-wave ports are used. This distance can be
increased to 10 kilometers by using a Long-wave Fibre Channel port
on the hubs or switches. The distance can be increased to 80 kilometers
if Finisar (Long-haul) GBICs are used in Fibre Channel switches
(hubs are not supported for this distance). If DWDM links are used,
the maximum distance between the data centers is 100 kilometers.
There must be at least two
alternately routed networking links between each primary data center
to prevent the “backhoe problem”. The “backhoe
problem” can occur when all cables are routed through a
single trench and a tractor on a construction job severs all cables and
disables all communications between the data centers. It is allowable
to have only a single network link routed from each primary data
center to the third location, however in order to survive the loss
of the network link between a primary data center and the arbitrator
data center, the network routing should be configured so that a
primary data center can also reach the arbitrator via a route which
passes through the other primary data center.
There must be at least two
alternately routed Fibre Channel Data Replication links between
each data center. If a third location is used for arbitrator nodes,
no Fibre Channel Data Replication links are required for third location.
Fibre Channel hubs are only
supported for distances up to 10 kilometers. For distances longer
than 10 kilometers, Fibre Channel switches are required. Fibre Channel
switches are always the preferred solution, since they offer much
better performance than Fibre Channel hubs, which only support Fibre
Channel Arbitrated loop mode.
Refer to the HP
Configuration Guide (available through your HP representative)
for a list of supported FibreChannel hardware.