User guide

Technical white paper | HP Enterprise Virtual Array Storage and VMware vSphere 4.x and 5.x configuration best practices
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Controller connections
As shown in Figures 10 and 11, Fibre Channel ports FP1 and FP2 on each controller are connected to the 1GbE iSCSI Module
and 10GbE iSCSI/FCoE Module respectively. For redundancy each array controller has a connection to the 1GbE iSCSI Module
available in the other controller.
• Controller A FP1 connects to Mezz 1 Port 1 (M
1
P
1
)
• Controller B FP1 connects to Mezz1 Port 2 (M
1
P
2
)
• Controller A FP2 connects to Mezz 2 Port 1(M
2
P
1
)
• Controller B FP2 connects to Mezz 2 Port 2 (M
2
P
2
)
The controllers to Mezz connections are all Fibre Channel internal connections. This is similar to connecting an EVA to an
MPX200 using physical front-end Fibre Channel ports, except that with the Mezz option, the connections are internal to the
controller.
Mezz: LUN groups and iSCSI targets
Within the Mezz, LUN groups are defined. These groups can be seen as virtual buckets that hold LUNs for iSCSI presentation
to hosts. By design, the array defines four LUN groups and each LUN group has a theoretical limit of 1024 LUNs; however, in
practice it can support up to 256 LUNs. Each group also spans the iSCSI Module in both controllers. With the use of N-Port
Virtualization (NPIV), each LUN group has four initiator connections to the EVA controllers; one connection through each of
the Mezz ports M
1
P
1,
M
1
P
2,
M
2
P
1,
and M
2
P
2
. In Figures 10 and 11, the port numbers 00, 01, 02, 03 below each Mezz port,
represents these NPIV initiator connections. Since the P6000/EVA allows up to 256 LUNs per initiator each of the NPIV port
numbers in each group could theoretically access 256 individual LUNs. However for redundancy reasons all four NPIV ports
in a iSCSI Module group must expose access to the same LUNs. For this, the maximum number of addressable LUNs per
group is 256.
Each group has 4 NPIV connections to the EVA controllers; two connections to each EVA controller; which yields two iSCSI
targets per group for each iSCSI Module. A total of 8 iSCSI targets are created in this fashion per iSCSI Module and all 8
targets are mapped for host access through each GbE port on the iSCSI Module.
When a LUN is created via Command View EVA for presentation to a host through iSCSI, it is created and assigned to one of
the available LUN groups. This assignment is important because it has a direct relation to the iSCSI targets the LUN will be
accessible through by the host. In Figure 10, assuming the LUN shown on Controller A was created in Group 1 (Group
highlighted in black), then this LUN would only be accessible via each GbE port through the iSCSI targets:
• CA-FP1-G1-M1: ControllerA, FP1, Group1, Mezz1
• CB-FP1-G1-M1: ControllerB, FP1, Group1, Mezz1
• CA-FP2-G1-M2: ControllerA, FP2, Group1, Mezz2
• CB-FP2-G1-M2: ControllerB, FP2, Group1, Mezz2
All the other iSCSI targets shown in the Figure 10/11 will not expose this LUN to hosts because those iSCSI targets do not
connect to Group 1.
Front-end GbE and FC ports
The 8 iSCSI targets on each controller built from the iSCSI Module connections are mapped to each GbE port. For example,
on the 1GbE iSCSI Module, each of the 8 1GbE ports per iSCSI Module will allow access to all iSCSI targets. Similarly, on the
10GbE iSCSI Module, the 8 iSCSI targets per iSCSI Module are mapped to each of the two 10GbE ports on each iSCSI Module.
ESX connectivity to EVA iSCSI
Availability consideration
ESX 4.x and 5.x allow up to eight iSCSI paths per LUN. When connected to an EVA with the 1GbE iSCSI Module option careful
configuration steps must be taken to avoid the possibility of exhausting all eight iSCSI paths per LUN without having the
proper high availability in the environment.
As ESX detects paths to LUNs during LUN discovery, it is possible that ESX will discover all eight iSCSI targets hence paths to
a LUN through controller 1 before discovering any paths to LUNs through controller 2. Figure 12 below, illustrates this
logical connection and assumes that the same physical connections are made to controller 2.