iSCSI

Introduction

Internet SCSI is one of several block protocols supported by the appliance for sharing SCSI based storage.

Target Configuration

When using the iSCSI protocol, the target portal refers to the unique combination of an IP address and TCP port number by which an initiator can contact a target.

When using the iSCSI protocol, a target portal group is a collection of target portals. Target portal groups are managed transparently; each network interface has a corresponding target portal group with that interface's active addresses. Binding a target to an interface advertises that iSCSI target using the portal group associated with that interface.

An IQN (iSCSI qualified name) is the unique identifier of a device in an iSCSI network. iSCSI uses the form iqn.date.authority:uniqueid for IQNs. For example, the appliance may use the IQN: iqn.1986-03.com.sun:02:c7824a5b-f3ea-6038-c79d-ca443337d92c to identify one of its iSCSI targets. This name shows that this is an iSCSI device built by a company registered in March of 1986. The naming authority is just the DNS name of the company reversed, in this case, "com.sun". Everything following is a unique ID that Sun uses to identify the target.

In addition to those properties, the BUI indicates whether a target is online or offline:

icon description Target is online Target is offline

Clustering Considerations

On clustered platforms, targets which have at least one active interface on that cluster node will be online. Take care when assigning interfaces to targets; a target may be configured to use portal groups on disjoint head nodes. In that situation, the target will be online on both heads yet will export different LUNs depending on the storage owned by each head node. As network interfaces migrate between cluster heads as part of takeover/failback or ownership changes, iSCSI targets will move online and offline as their respective network interfaces are imported and exported.

Targets which are bound to an IPMP interface will be advertised only via the addresses of that IPMP group. That target will not be reachable via that group's test addresses. Targets bound to interfaces built on top of a LACP aggregation will use the address of that aggregation. If a LACP aggregation is added to an IPMP group, a target can no longer use that aggregation's interface, as that address will become an IPMP test address.

Initiator Configuration

iSCSI initiators have the following configurable properties.

Planning Client Configuration

When planning your iSCSI client configuration, you'll need the following information:

• What initiators (and their IQNs) will be accessing the SAN?

• If you plan on using CHAP authentication, what CHAP credentials does each initiator use?

• How many iSCSI disks (LUNs) are required, and how big should they be?

• Do the LUNs need to be shared between multiple initiators?

To allow the Appliance to perform CHAP authentication using RADIUS, the following pieces of information must match:

• The Appliance must specify the address of the RADIUS server and a secret to use when communicating with this RADIUS server

• The RADIUS server (e.g. in its clients file) must have an entry giving the address of this Appliance and specifying the same secret as above

• The RADIUS server (e.g. in its users file) must have an entry giving the CHAP name and matching CHAP secret of each initiator

• If the initiator uses its IQN name as its CHAP name (the recommended configuration) then the Appliance does not need a separate Initiator entry for each Initiator box -- the RADIUS server can perform all authentication steps.

• If the initiator uses a separate CHAP name, then the Appliance must have an Initiator entry for that initiator that specifies the mapping from IQN name to CHAP name. This Initiator entry does NOT need to specify the CHAP secret for the initiator.

Solaris iSCSI/iSER and MPxIO Considerations

MPxIO supports target port aggregation and availability in Solaris iSCSI configurations that configure multiple sessions per target (MS/T) on the iSCSI initiator.

• Use IPMP for aggregation and failover of two or more NICs.

• A basic configuration for an iSCSI host is a server with two NICs that are dedicated to iSCSI traffic. The NICs are configured by using IPMP. Additional NICs are provided for non-iSCSI traffic to optimize performance.

• Active multipathing can only be achieved by using the Solaris iSCSI MS/T feature, and the failover and redundancy of an IPMP configuration.

• *If one NIC fails in an IPMP configuration, IPMP handles the failover. The MPxIO driver does not notice the failure. In a non-IPMP configuration, the MPxIO driver fails and offlines the path.

• *If one target port fails in an IPMP configuration, the MPxIO driver notices the failure and provides the failover. In a non-IPMP configuration, the MPxIO driver notices the failure and provides the failover.

• For more information about using the Solaris iSCSI MS/T feature with IPMP and multipathing, see SunSolve Infodoc 207607, Understanding an iSCSI MS/T multi-path configuration.

• For information about configuring multiple sessions per target, see How to Enable Multiple iSCSI Sessions for a Target in the following document: http://docs.sun.com/app/docs/doc/817-5093/gcawf

• For information about configuring IPMP, see Part VI, IPMP, in System Administration Guide: IP Services, in the following document: http://docs.sun.com/app/docs/doc/816-4554/ipmptm-1

Troubleshooting

For tips on troubleshooting common iSCSI misconfiguration, see the iSCSI section.

Observing Performance

iSCSI performance can be observed via analytics, whereby one can breakdown operations or throughput by initiator, target, or LUN.

BUI

Creating an Analytics Worksheet

To create an analytics worksheet for observing operations by initiator, complete the following:

1. Go to the Analytics screen.

2. Click the add icon for Add Statistic.

A menu of all statistics appears.

3. Select iSCSI operations > Broken down by initiator under the Protocols section of the menu.

A graph of the current operations by initiator appears.

4. To observe more detailed analytics, select the initiator from the field to the left of the graph and click the icon.

A menu of detailed analytics appears.

CLI

Adding an iSCSI target with an auto-generated IQN

ahi:configuration san targets iscsi> create
ahi:configuration san targets iscsi target (uncommitted)> set alias="Target 0"
ahi:configuration san targets iscsi target (uncommitted)> set auth=none
ahi:configuration san targets iscsi target (uncommitted)> set interfaces=nge1 
ahi:configuration san targets iscsi target (uncommitted)> commit
ahi:configuration san targets iscsi> list
TARGET     ALIAS          
target-000 Target 0       
           |
           +-> IQN
               iqn.1986-03.com.sun:02:daf0161f-9f5d-e01a-b5c5-e1efa9578416

Adding an iSCSI target with a specific IQN and RADIUS authentication

ahi:configuration san targets iscsi> create
ahi:configuration san targets iscsi target (uncommitted)> set alias="Target 1"
ahi:configuration san targets iscsi target (uncommitted)>
     set iqn=iqn.2001-02.com.acme:12345
ahi:configuration san targets iscsi target (uncommitted)> set auth=radius 
ahi:configuration san targets iscsi target (uncommitted)> set interfaces=nge1 
ahi:configuration san targets iscsi target (uncommitted)> commit
ahi:configuration san targets iscsi> list
TARGET     ALIAS          
target-000 Target 0       
           |
           +-> IQN
               iqn.1986-03.com.sun:02:daf0161f-9f5d-e01a-b5c5-e1efa9578416
target-001 Target 1       
           |
           +-> IQN
               iqn.2001-02.com.acme:12345

Adding an iSCSI initiator which uses CHAP authentication

ahi:configuration san initiators iscsi> create
ahi:configuration san initiators iscsi initiator (uncommitted)> 
     set initiator=iqn.2001-02.com.acme:initiator12345
ahi:configuration san initiators iscsi initiator (uncommitted)> set alias="Init 0"
ahi:configuration san initiators iscsi initiator (uncommitted)>
     set chapuser=thisismychapuser
ahi:configuration san initiators iscsi initiator (uncommitted)>
     set chapsecret=123456789012abc
ahi:configuration san initiators iscsi initiator (uncommitted)> commit
ahi:configuration san initiators iscsi> list
NAME          ALIAS
initiator-000 Init 0
              |
              +-> INITIATOR
                  iqn.2001-02.com.acme:initiator12345

Adding an iSCSI target group

ahi:configuration san targets iscsi groups> create
ahi:configuration san targets iscsi group (uncommitted)> set name=tg0
ahi:configuration san targets iscsi group (uncommitted)> 
    set targets=iqn.2001-02.com.acme:12345,
                iqn.1986-03.com.sun:02:daf0161f-9f5d-e01a-b5c5-e1efa9578416
ahi:configuration san targets iscsi group (uncommitted)> commit
ahi:configuration san targets iscsi groups> list
GROUP     NAME
group-000 tg0
          |
          +-> TARGETS
              iqn.2001-02.com.acme:12345
              iqn.1986-03.com.sun:02:daf0161f-9f5d-e01a-b5c5-e1efa9578416

Adding an iSCSI initiator group

ahi:configuration san initiators iscsi groups> create 
ahi:configuration san initiators iscsi group (uncommitted)> set name=ig0
ahi:configuration san initiators iscsi group (uncommitted)> 
    set initiators=iqn.2001-02.com.acme:initiator12345
ahi:configuration san initiators iscsi group (uncommitted)> commit
ahi:configuration san initiators iscsi groups> list
GROUP     NAME
group-000 ig0
          |
          +-> INITIATORS
             iqn.2001-02.com.acme:initiator12345