Storage Area Network Configurations for RA8000/ESA12000 on Windows NT-Intel Application Note

Application Note
AA–RHH6B–TE Page 17
SAN Fabric Configuration 4 – Four FC Switches, Cascaded High Availability
Fault Tolerant Fabric, Secure Path, Controller
Multiple-Bus Failover Mode, Integrated EBS
SAN Fabric configuration 4 (Figure 5) is a high availability storage cascaded switch configuration
that provides increased server, disk, and tape storage connectivity capabilities. This configuration
uses two separate Fabrics to provide two data paths between servers and disk storage configured in
Multiple-Bus failover mode. Tape storage can be configured on one of the Fabrics to provide backup
and restore capabilities. Up to 26 separate (non-cooperating) servers or up to 13 pairs of clustered
(cooperating) servers can be connected through 4 16-port FC switches to 4 storage systems. With 8-
port FC switches up to 6 servers can be connected to 1 storage system. With either switch type the
number of storage systems can be increased if the number of servers is reduced to provide switch
ports for storage. This SAN configuration utilizes the high availability features of controller Multiple-
Bus failover and Compaq Secure Path for Windows NT software. With 2 FC HBA’s in each server
and 4 FC switches in 2 separate isolated Fabrics, a second separate path to the storage is provided to
each server. The 2 switch pairs form isolated Fabrics providing the highest level of storage path fault
tolerance should a failure occur with any path component - FC HBA, FC Switch, Fabric path
interconnect, or storage controller. Non-HA configured servers and storage configured in Transparent
Failover Mode are supported in this configuration, however access may be limited to one or the other
of the two Fabrics unless 2 FC HBAs are utilized, each connected to a different Fabric.
Figure 5 Four Switches, Cascaded HA Fault Tolerant Fabric Configuration Example
Active
Active
Active
Active
Port 1 A Port 2
Port 1 B Port 2
24 Disks
24 Disks
RA8000 or
ESA 12000 FC
Dual Controller
24 Disks
FC Switch #2
FC Switch #4
FC Switch #1
FC Switch #3
Windows NT
Intel
Server
FC HBA1 FC HBA2
Windows NT
Intel
Server
FC HBA1 FC HBA2
Windows NT
Intel
Server
FC HBA1 FC HBA2
NT Cluster
Active
ActiveStandby
Standby
Port 1 A Port 2
Port 1 B Port 2
24 Disks
24 Disks
RA8000 or
ESA 12000 FC
Dual Controller
24 Disks
Active Active
Active Active
Port 1 A Port 2
Port 1 B Port 2
24 Disks
24 Disks
RA8000 or
ESA 12000 FC
Dual Controller
24 Disks
Windows NT
Intel
Server
FC HBA
SHR-1554