Configuring iSCSI Initiators Tasks

This is a general list of tasks associated with configuring iSCSI initiators. Some of the tasks are optional depending on your network configuration needs. Some of the links below will take you to separate documents that describe network configuration and target configuration.

• Identifying Oracle Solaris iSCSI Software and Hardware Requirements

• Configuring and Administering Oracle Solaris 11.1 Networks

• Chapter 11, Configuring Storage Devices With COMSTAR (Tasks), in Oracle Solaris 11.1 Administration: Devices and File Systems

• Configuring Dynamic or Static Target Discovery

• How to Configure an iSCSI Initiator

• How to Access iSCSI Disks

• Configuring Authentication in Your iSCSI-Based Storage Network

• Setting Up iSCSI Multipathed Devices in Oracle Solaris

• Monitoring Your iSCSI Configuration

iSCSI Terminology

Review the following terminology before configuring iSCSI targets and initiators.

Recommended iSCSI Configuration Practices

Review the following iSCSI recommendations before configuring iSCSI devices in your network.

• Devices

  • Consider using multipathed device paths for increased availability.

  • Multiple connections per session (MCS) support allow multiple TCP/IP connections from the initiator to the target for the same iSCSI session.

• Network

  • Deploy iSCSI devices in a fast (gigE or better), dedicated network.

  • Use jumbo frames, if possible to allow more data to be transferred in each Ethernet transaction to reduce the number of frames.

  • Use CAT6 rated cables for Gigabit network infrastructures.

  • Segregate iSCSI storage networks from your local area network traffic

  • Configure multiple sessions or connections to utilize multiple threads in TCP/IP stack

  • Consider TCP tuning, such as disabling Nagle algorithm

• Security

  • In addition to physical security, use CHAP authentication, which ensures that each host has its own password.

  • Consider using iSNS target discovery domains, which enhance security by providing access control to targets that are not enabled with their own access controls, while limiting the logon process of each initiator to a relevant subset of the available targets in the network.

Configuring Dynamic or Static Target Discovery

Determine whether you want to configure one of the dynamic device discovery methods or use static iSCSI initiator targets to perform device discovery.

• Dynamic device discovery – Two dynamic device discovery methods are available:

  • SendTargets – If an iSCSI node exposes a large number of targets, such as an iSCSI to Fibre-Channel bridge, you can supply the iSCSI node IP address/port combination and allow the iSCSI initiator to use the SendTargets features to perform the device discovery.

  • iSNS – The Internet Storage Name Service (iSNS) allows the iSCSI initiator to discover the targets to which it has access using as little configuration information as possible. It also provides state change notification to notify the iSCSI initiator when changes in the operational state of storage nodes occur. To use the iSNS discovery method, you can supply the iSNS server address/port combination and allow the iSCSI initiator to query the iSNS servers that you specified to perform the device discovery. The default port for the iSNS server is 3205. For more information about iSNS, see RFC 4171:

    http://www.ietf.org/rfc/rfc4171.txt

    The iSNS discovery service provides an administrative model to discover all targets on a network.

    For more information about setting up iSNS support in Oracle Solaris, see Chapter 12, Configuring and Managing the Oracle Solaris Internet Storage Name Service (iSNS), in Oracle Solaris 11.1 Administration: Devices and File Systems.

• Static device discovery – If an iSCSI node has few targets or if you want to restrict the targets that the initiator attempts to access, you can statically configure the target-name by using the following static target address naming convention:

  target,target-address[:port-number]

  You can determine the static target address from the array's management tool.

How to Configure an iSCSI Initiator

Part of the initiator configuration process is to identify the iSCSI target discovery method, which presents an initiator with a list of available targets. You can configure iSCSI targets for static, SendTargets, or iSNS dynamic discovery. Dynamic discovery using the SendTargets option is the optimum configuration for an iSCSI initiator that accesses a large number of targets, such over an iSCSI to Fibre Channel bridge. SendTargets dynamic discovery requires the IP address and port combination of the iSCSI target for the iSCSI initiator to perform the target discovery. The most common discovery method is SendTargets.

When configuring the target discovery method, you must provide the following information, depending on which method you choose:

• SendTargets – Target IP address

• iSNS – iSNS server address

• Static – Target IP address and target name

For more information about configuring target discovery methods, see Configuring Dynamic or Static Target Discovery.

1. Enable the iSCSI initiator service.

   initiator# svcadm enable network/iscsi/initiator

2. Verify the target's name and IP address while logged in to the server that is providing the target.

   target# ipadm show-addr
   ADDROBJ           TYPE     STATE        ADDR
   lo0/v4            static   ok           127.0.0.1/8
   e1000g0/_b        dhcp     ok           1.2.3.4/24
   lo0/v6            static   ok           ::1/128
   e1000g0/_a        addrconf ok           fe80::123:1234:fe27:360c/10
   target# itadm list-target -v
   TARGET NAME                                                  STATE    SESSIONS 
   iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c123456  online   0        
           alias:                  -
           auth:                   none (defaults)
           targetchapuser:         -
           targetchapsecret:       unset
           tpg-tags:               default

3. Configure the target to be statically discovered.

   initiator# iscsiadm add static-config iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c123456,
   1.2.3.4

4. Review the static configuration information.

   initiator# iscsiadm list static-config
   Static Configuration Target: iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c123456,
   1.2.3.4:3260

   The iSCSI connection is not initiated until the discovery method is enabled. See the next step.

5. Configure one of the following target discovery methods:

   • If you have configured a dynamically discovered (SendTargets) target, configure the SendTargets discovery method.

     initiator# iscsiadm add discovery-address 1.2.3.4

   • If you have configured a dynamically discovered (iSNS) target, configure the iSNS discovery method.

     initiator# iscsiadm add isns-server 1.2.3.4

6. Enable one of the following the target discovery methods:

   • If you have configured a dynamically discovered (SendTargets) target, enable the SendTargets discovery method.

     initiator# iscsiadm modify discovery --sendtargets enable

   • If you have configured a dynamically discovered (iSNS) target, enable the iSNS discovery method.

     initiator# iscsiadm modify discovery --iSNS enable

   • If you have configured static targets, enable the static target discovery method.

     initiator# iscsiadm modify discovery --static enable

7. Reconfigure the /dev namespace to recognize the iSCSI disk, if necessary.

   initiator# devfsadm -i iscsi

How to Access iSCSI Disks

After the devices have been discovered by the Oracle Solaris iSCSI initiator, the login negotiation occurs automatically. The Oracle Solaris iSCSI driver determines the number of available LUs and creates the device nodes. Then, the iSCSI devices can be treated as any other SCSI device.

You can create a ZFS storage pool on the LU and then create a ZFS file system.

You can view the iSCSI disks on the local system by using the format utility.

1. Review the iSCSI LU information in the format output.

   initiator# format
          0. c0t600144F0B5418B0000004DDAC7C10001d0 <SUN-COMSTAR-1.0 cyl 1022 alt 2 hd 128 sec 32>
             /scsi_vhci/disk@g600144f0b5418b0000004ddac7c10001
          1. c8t0d0 <Sun-STK RAID INT-V1.0 cyl 17830 alt 2 hd 255 sec 63>
             /pci@0,0/pci10de,375@f/pci108e,286@0/disk@0,0
          2. c8t1d0 <Sun-STK RAID INT-V1.0-136.61GB>
             /pci@0,0/pci10de,375@f/pci108e,286@0/disk@1,0
          3. c8t2d0 <Sun-STK RAID INT-V1.0-136.61GB>
             /pci@0,0/pci10de,375@f/pci108e,286@0/disk@2,0
          4. c8t3d0 <Sun-STK RAID INT-V1.0 cyl 17830 alt 2 hd 255 sec 63>
             /pci@0,0/pci10de,375@f/pci108e,286@0/disk@3,0
   Specify disk (enter its number): 0
   selecting c0t600144F0B5418B0000004DDAC7C10001d0
   [disk formatted]

   In the above output, disk 0 is an iSCSI LU under MPxIO control. Disks 1-4 are local disks.

2. You can create a ZFS storage pool and ZFS file systems on the iSCSI LU.

   initiator# zpool create pool-name c0t600144F0B5418B0000004DDAC7C10001d0
   initiator# zfs create pool-name/fs-name

   The ZFS file system is automatically mounted when created and is remounted at boot time.

How to Remove Discovered Target Devices

The associated targets are logged out after you perform any of the following actions:

• Remove a discovery address

• Remove an iSNS server

• Remove a static configuration

• Disable a discovery method

If these associated targets are still in use, for example, they have mounted file systems, the logout of these devices will fail, and they will remain on the active target list.

This optional procedure assumes that you are logged in to the local system where access to an target device has already been configured.

1. Become an administrator.
2. (Optional) Disable an iSCSI target discovery method by using one of the following:

   • If you need to disable the SendTargets discovery method, use the following command:

     initiator# iscsiadm modify discovery --sendtargets disable

   • If you need to disable the iSNS discovery method, use the following command:

     initiator# iscsiadm modify discovery --iSNS disable

   • If you need to disable the static target discovery method, use the following command:

     initiator# iscsiadm modify discovery --static disable

3. Remove an iSCSI device discovery entry by using one of the following:

   • Remove an iSCSI SendTargets discovery entry.

     For example:

     initiator# iscsiadm remove discovery-address 1.2.3.4:3260

   • Remove an iSCSI iSNS discovery entry.

     For example:

     # iscsiadm remove isns-server 1.2.3.4:3205

   • Remove a static iSCSI discovery entry.

     For example:

     initiator# iscsiadm remove static-config eui.5000ABCD78945E2B,1.2.3.4

   ---

   Note - If you attempt to disable or remove a discovery entry that has an associated logical unit (LU) in use, the disable or remove operation fails with the following message:

   logical unit in use

   If this errors occurs, stop all associated I/O on the LU, unmount the file systems. Then, repeat the disable or remove operation.

   ---

4. Remove the iSCSI target device.

   For example:

   target# itadm delete-target target-IQN

   This command might error if the target is still online or busy:

   The target is online or busy. Use the -f (force) option, or 'stmfadm offline-target 
   iqn.1986-03.com.sun:02:99619b8a-a4dc-4cfb-93f0-ee3de1234567'
   itadm delete-target failed with error 16