Configuring Dell EqualLogic storage systems

The system supports iSCSI connections to Dell EqualLogic storage systems.

Unlike Storwize family systems, Dell EqualLogic systems have separate IQNs for each LUN on these storage systems. Since the maximum number of iSCSI sessions is limited, only two nodes in a single I/O group can connect to any single Dell storage system. Therefore, connections to these storage systems must be configured for a single I/O group, even if there is more than one I/O group on the system.

Also, unlike Storwize family systems, you connect each iSCSI initiator (node) to one array port per volume. With Dell EqualLogic systems, the recommendation is to complete all SendTargets discovery and session establishment to the group IP address only. Load balancing across target arrays and array ports is achieved by Dell EqualLogic by using login redirection.

The following graphic shows the iSCSI configuration between the system and a Dell EqualLogic system that is used as external storage.

Figure 1. Dell EqualLogic storage systems iSCSI configuration example
This figure shows an example of a Dell EqualLogic iSCSI configuration.

Best practices for establishing connectivity to a Dell EqualLogic storage system

Configure the Dell EqualLogic array and switched connectivity to the Dell EqualLogic storage system by following the instructions in the Dell Configuration Guide.
Identify the I/O group whose nodes discover and connect to the Dell EqualLogic storage system.
Understand the number of source ports per initiator node that must be used for connectivity to the target Dell EqualLogic storage system and configure the storage or storage_6 flag for each such source Ethernet port.
Understand the maximum number of volumes or LUNs (represented by IQN) that are to be managed by the initiator.
If x is the number of source ports to be used for connectivity to Dell EqualLogic and y is the number of Dell EqualLogic volumes (IQNs) to be managed by the initiator nodes, then for load balancing, the number of LUNs that must be connected per initiator storage enabled Ethernet port is z = y/x.

To add a Dell EqualLogic storage system, complete these steps:

Using the management GUI

In the management GUI, select Pools > External Storage > Add External iSCSI Storage.
Select Dell for the type of external storage.
Enter the following values to define the connection between the source ports and the target ports on the external storage:
I/O Group

Select the I/O group where the source ports are on the system. Only source ports in the nodes of the specified I/O group discover target ports on external storage.

Target port on remote storage

Group IP address for the Dell EqualLogic array that receives the request from source ports in the specified I/O group.

CHAP secret

Site

Specify the site that this storage system is associated with.
Note: The storage system must be associated with a site in systems with HyperSwap configurations.

Site

Specify the site that this storage system is associated with. Site definitions are only required on systems that are configured with multiple-site topologies, which are used for high availability and disaster recovery. The storage system must be associated with a site in systems with these configurations.

Source port 1

Enter the first source port ID that is used as the initiator for the iSCSI connection between the node and the storage system.

Source port 2

Enter the second source port ID that is used as the initiator for the iSCSI connection between the node and the storage system.
Click Next.
From the list of available IQNs, select the IQNs that are listed as MDisks to the system.
Click Add.

Using the command-line interface (CLI)

Enter the following commands to discover and configure target ports on Dell EqualLogic storage systems. If you use CHAP to secure iSCSI connections on the system, enter the current CHAP secret.

To configure IPs on the source with -storage/-storage_6 as yes, enter the following command:
```
cfgportip -node node_name -ip_6 ipv6addr -prefix_6 prefix
 -gw_6 ipv6gw -storage_6 yes port_id
```
where the port ID is the Ethernet port number as visible in the output command lsportip.
To configure an IPv4 address, enter the following command:
```
cfgportip -node node_name -ip ipv4addr -gw ipv4gw
 -mask subnet_mask -storage yes  port_id
```
where the port ID is the Ethernet port number as visible in output command lsportip.
Enter the following command to manually discover the iSCSI target with the provided IP and CHAP secret (if configured) by using source port 1 of I/O group 0:
```
svctask detectiscsistorageportcandidate -targetip Dell_Group_IP
 -srcportid 1 -username target_user_name -chapsecret target_chap -iogrp 0 
```
Enter the lsiscsistorageportcandidate command to list the discovered targets, which equal the number of LUNs that are mapped from Dell EqualLogic to the initiator system. If the number of LUNs is y, the output of lsiscsistorageportcandidate shows y rows with row_id 0 - (y-1):
```
svcinfo lsiscsistorageportcandidate
```
After the discovery is successful, you can add sessions to the target by using the following command:
```
svctask addiscsistorageport -username target_user_name
 -chapsecret target_chap -iogrp 0 row_id
```
If two source ports per initiator node are to be used for connectivity to the Dell EqualLogic storage system, run the svctask addiscsistorageport command for row_ids 0 to (y/2 - 1).

Repeat step 3 with -srcportid 2, considering 2 is the srcport number of the second port to connect to.

svctask detectiscsistorageportcandidate -targetip Dell_Group_IP
 -srcportid 1 -username target_user_name -chapsecret target_chap -iogrp 0

Enter the lsiscsistorageport command to list the status of the discovered targets. The output is the same as that in step 4.
After the discovery is successful, you can add sessions to the remaining target volumes or LUNs by running the following command with row_ids y/2 to y-1.
```
svctask addiscsistorageport -username target_user_name
 -chapsecret target_chap -iogrp 0 row_id
```
Enter the lsiscsistorageport command to list the status of the initiator and target for each session in separate rows.
Enter the lsiscistorageport row_id command to list the detailed status of source node connectivity via the respective ports to the target. The row ID is taken from lsiscsistorageport command.