Configuring IBM Spectrum Accelerate storage systems

The system supports iSCSI connections to all external storage systems that are built with IBM Spectrum Accelerate.

IBM Spectrum Accelerate storage systems support horizontal scale-out capability, which means a single system can have 3 - 15 nodes as targets. However, all nodes have a single IQN that handles all connections. To provide fault tolerance, configure at least two target nodes to two or more source ports. More connections can be configured between a source system and target dependent on availability of source ports with storage connectivity enabled.

The graphic describes the connection between the system and an IBM Spectrum Accelerate external storage system. In this diagram, the system is composed of two I/O groups with two nodes. Each node has a maximum of four initiator ports with two configured through two switches to the target ports on the storage systems. The other two ports on each node are not configured. The first ports (orange) on each initiator and target node are connected through Ethernet switch 1. The second ports (blue) on each initiator and target node are connected through Ethernet switch 2. All target nodes on IBM Spectrum Accelerate storage systems use a single, common iSCSI target IQN and all volumes are accessible through all target nodes. Connectivity from the initiator system must be established to two or more target nodes. Available source ports on the system must be configured to connect to external storage. If a node is not enabled for external storage, ports on that node cannot be used as source ports for the connection. To enable a node for storage, select Settings > Network > Ethernet Ports. Right-click the port and select Modify Storage Ports to enable the port for iSCSI connections to storage systems.

This figure shows an example of an IBM Spectrum Accelerate iSCSI configuration. — Figure 1. IBM Spectrum Accelerate iSCSI configuration example

In the graphic, initiator ports IPA, IPE, IPI, and IPM are connected through Ethernet switch 1 to the first target port on target node 1 (IP1). The initiator ports IPB, IPF, IPJ, and IPN are connected through Ethernet switch 2 on the target node 2 (IP5). Because IBM Spectrum Accelerate storage systems can have many target nodes, you can connect to as many target ports across nodes as the number of source ports. Any additional source ports must be configured for storage connectivity.

When you define source port connections, the configuration applies to all the ports on the system. For example, target port IP1 on node 1 of the target node 1 is the target port for source ports IPA, IPE, IPI, and IPM. The target port of target node 2 is the target port for source ports IPB, IPF, IPJ, and IPN.

In the example configuration, extra ports remain unconfigured but can be connected to increase throughput. In the graphic, the initiator and target nodes each support four ports. Initiator ports IPC, IPD, IPG, IPH, IPK, IPL, IPO, and IPP remain unconfigured. On the target nodes, ports IP2, IP3, IP4, IP6, IP7, and IP8 are also unconfigured. To increase throughput, initiator ports IPC, IPG, IPK, and IPO can be connected through Ethernet switch 1 to any unused target port across target node 1-N. When these connections are configured, another path between the source and target nodes is created.

Using the management GUI

To add an iSCSI-attached IBM Spectrum Accelerate storage system, complete these steps:

In the management GUI, select Pools > External Storage > Add External iSCSI Storage.
Select IBM Spectrum Accelerate 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:

CHAP username

Enter the user name to associate with this connection. If the target storage system uses Challenge Handshake Authentication Protocol (CHAP) to authenticate connections, you must enter a user name. If you specify a user name, you must specify a CHAP secret. If you do not use CHAP, this value is not required.

CHAP secret

If CHAP is used to secure iSCSI connections on the system, enter the current CHAP secret. If you do not use CHAP, this value is not required.

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.

Source port 1 connections

Create connections from the source port to target ports on the IBM Spectrum Accelerate external storage system. You can configure as many source ports as necessary to connect to the IBM Spectrum Accelerate storage systems. For each source port, only one target port can be configured. If a source port is already being used, you cannot create a connection to a target port.

Select source port 1

Select the source port ID that is used as the initiator for the iSCSI connection between the node and the storage system. Click the plus (+) icon to add more source ports. You can configure as many source ports as you need for connectivity to each IBM Spectrum Accelerate system. For example, source port 1 is IPA in the graphic. While the graphic shows source ports 1 and 2 being used as the source ports, it is not mandatory to use the ports in any order. Any or all ports can be used. Similarly, it is not required that source port 1 must be connected to target port 1 and source port 2 must be connected to target port 2. The source and target ports can be selected in any order based on how traffic from different ports needs to be isolated.

Target port on remote storage 1

Enter the IP address for the target port on the first external storage. Click the plus (+) icon to add more target ports for the selected source ports. You can associate only one IP address from each module on storage system to each source port.

Source port 2 connections

Create connections from the source port to target ports on the IBM Spectrum Accelerate external storage system. You can configure as many source ports as necessary to connect to the IBM Spectrum Accelerate storage systems. For each source port, only one target port can be configured. If a source port is already being used, you cannot create a connection to a target port.

Select source port 2

Select the source port ID that is used as the source for the iSCSI connection between the node and the storage system. For example, source port 2 is IPB in the graphic. While the graphic shows source ports 1 and 2 being used as the source ports, it is not mandatory to use the ports in any order. Any or all ports can be used. Similarly, it is not required that source port 1 must be connected to target port 1 and source port 2 must be connected to target port 2. The source and target ports can be selected in any order based on how traffic from different ports needs to be isolated.

Target port on remote storage 2

Enter the IP address for the target port on the second IBM Spectrum Accelerate. Click the plus (+) icon to add more target ports for the selected source ports. You can associate only one IP address from each module on IBM Spectrum Accelerate storage system to each source port.
Click Next.

Using the command-line interface (CLI)

Enter the following commands to discover and configure target ports on IBM Spectrum Accelerate storage systems. These examples use the port numbers that are included in the figure. If you use CHAP to secure iSCSI connections on the system, enter the current CHAP secret. A CHAP secret is not required. Also, determine whether to specify I/O group or system-wide discovery and session establishment.

To configure IPs on the source with -storage as yes, enter the following command:
```
mkip -node node_name -ip <ipv6addr/ipv4addr> -prefix prefix
-gw <ipv6gw/ipv4gw> port_id
```
where the port ID is IPA, IPB, IPE, and IPF.
Enter the following command to manually discover the iSCSI target with the provided IP and CHAP secret (if configured):
```
svctask detectiscsistorageportcandidate -targetip IP1
 -srcportid 1 -username user1 -chapsecret password
```
(-srcportid 1 is shown as IPA, IPE, IPI, and IPM in the figure.)
Enter the lsiscsistorageportcandidate command to list the status of the most recently discovered target.
After the discovery is successful, you can add sessions to the target by using the following command:
```
svctask addiscsistorageport -username user1  -chapsecret password 0
```
where 0 is the row ID of the lsiscsistorageportcandidate command in step 3.
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 statuses of source node connectivity via their respective ports to the target. The row ID is taken from lsiscsistorageport command:
Repeat this sequence for each target IP (IP2, IP5, and so on). Choose a different source port each time. Configure the target IP for at least two target nodes.