Bull Escala EPC400 Connecting Manual page 151

The micro-modem referenced ME62AF (said mini-driver) in Blackbox catalogues is an
example of what you can purchase to extend RS232 lines.
The physical characteristics are:
• Protocol
• Speed
• Transmission Line
• Operation
• Connectors DTE/DCE
• Size
• Weight
The maximum length of a fibre link between two MIA is 500 meters. A pair of FC-AL hubs is
interconnected with a fiber cable (50m) and an MIA device on each FC-AL hub when the
distance between the two nodes does not exceed 500 meters.
The Escala EPC offer only contains the MIAs which are used to interconnect the FC-AL
hubs. The cabling between separate buildings or inside a building is out of scope of the
Escala product and must be performed by ad-hoc professional services. This also applies
for the extended RS232 lines used for the heartbeat mechanism of HACMP.
When a node fails, the service is recovered on the remote node, and the recovery is
transparent to the client in as much as the appropriate failover script exists at application
level.
However, on a site disaster, the client may have to reconnect to the node that has
automatically recovered the activity of the node of the destroyed site. This can be the case
when the router to the public network enabling the client to access the cluster was in the
destroyed site.
Case 2 – No IP Takeover
In that case the two distant nodes may not be on the same IP subnet. The heartbeat serial
line should be double if the two nodes are not connected to the same TCP-IP network.
When a node fails or a disaster happens on a site, the client has to connect to the peer
node where the service has been recovered. There is no transparent recovery.
Large Distances (under 10 km)
CAUTION:
The section only presents technologies that can allow theoretically to go beyond
500m. In any case, ad-hoc professional customer services are recommended for
constructing such solution.
The two Fibre Channel hubs are interconnect with fiber cable (9m) and Finisar device on
each hub when the distance exceeds 500m. IP takeover is only possible if there is LAN (the
two nodes must pertain to same subnet) that permits such distance between the nodes.
FDDI is an example of appropriate LAN technology in that case.
For a large distance, the micro-modem referenced ME657A-F (said pseudo-modem) can be
used for setting the heartbeat line.
The physical characteristics are:
• Protocol
• Speed
• Transmission Line
• Operation
• Connectors DTE/DCE
asynchronous
9.6 kbps
2 twisted pair (Wire gauge: 24-AWG, i.e. 0.5mm)
Full duplex, 4-wire
DB-25 female
1.3cm x 5.3cm x 10.9cm
0.1kg
asynchronous
9.6 kbps for distances up to 9.5km
2 twisted pair (Wire gauge: 24-AWG, i.e. 0.5mm)
Full duplex, 4-wire
DB-25 female
Disk Subsystems Cabling Requirements
10-41