Configuring iSCSI Devices With COMSTAR

You can set up and configure a COMSTAR Internet SCSI (iSCSI) target and make it available over the network. The iSCSI features can work over a normal Internet connection (such as Ethernet) using the standard iSCSI protocol. The iSCSI protocol also provides naming and discovery services, authentication services using CHAP and RADIUS, and centralized management through iSNS.

If the system has at least one InfiniBand (IB) Host Channel Adapter (HCA) and connectivity exists between the initiator and the target, the iSCSI connection uses iSCSI Extensions for RDMA (iSER) for enhanced data throughput. iSER used with an IB HCA provides high bandwidth, low CPU utilization, and a single network connection that multiple protocols can share.

The iSER target and initiator both use a component called iSCSI Data Mover to provide iSCSI connection services. Use of iSER is automatic whenever both the initiator and the target are configured to use IP addresses that correspond to IB-capable devices.

How to Enable the STMF Service

COMSTAR uses SMF to store its current, persistent configuration, such as logical unit mapping, host group definitions, and target group definitions. When the service is enabled during boot or when using the svcadm command, it clears any stale configuration data inside the kernel framework, and then reloads the configuration from the SMF repository into the driver. After the configuration is loaded, any changes that are made to the configuration are automatically updated inside the driver database, as well as inside the SMF repository. For example, any changes made through the stmfadm command are automatically updated in both areas.

The COMSTAR target mode framework runs as the stmf service. By default, the service is disabled. You must enable the service to use COMSTAR functionality. You can identify the service with the svcs command. If you have not rebooted the server since installing the group/feature/storage-server package, the service might not be enabled correctly.

Install the COMSTAR storage server software.

target# pkg install group/feature/storage-server
              Packages to install:    75
           Create boot environment:    No
               Services to restart:     7
DOWNLOAD                                  PKGS       FILES    XFER (MB)
Completed                                75/75   9555/9555  105.7/105.7

PHASE                                        ACTIONS
Install Phase                            13347/13347 

PHASE                                          ITEMS
Package State Update Phase                     75/75 
Image State Update Phase                         2/2 
Loading smf(5) service descriptions: 17/17
Loading smf(5) service descriptions: 3/3

PHASE                                          ITEMS
Reading Existing Index                           8/8 
Indexing Packages                              75/75
Indexing Packages                              75/75
Optimizing Index...

PHASE                                          ITEMS
Indexing Packages                            573/573

Either reboot the system or enable the stmf service.

target# svcadm enable stmf
# svcs stmf
STATE          STIME    FMRI
online         09:42:32 svc:/system/stmf:default

How to Back Up and Restore a COMSTAR Configuration

After you complete your COMSTAR configuration, make a copy that can be restored, if needed.

Become an administrator.

Export the current COMSTAR configuration.

# svccfg export -a stmf > COMSTAR.backup

If necessary, restore the exported configuration.
```
# svccfg import COMSTAR.backup
```

How to Create an iSCSI LUN

The logical unit provider for creating disk-type LUNs is called sbd. However, you must initialize the storage for the logical unit before you can share a disk-type LUN.

The disk volume provided by the server is referred to as the target. When the LUN is associated with an iSCSI target, it can be accessed by an iSCSI initiator.

The process for creating SCSI LUNs is as follows:

Initialize the storage for the LUN, also known as the backing store.
Create a SCSI LUN by using the backing store.

When a LUN is created, it is assigned a global unique identifier (GUID), for example, 600144F0B5418B0000004DDAC7C10001. The GUID is used to refer to the LUN in subsequent tasks, such as mapping a LUN to select hosts.

The following steps are completed on the system that is providing the storage device.

Create a ZFS storage pool.

target# zpool create sanpool mirror c2t3d0 c2t4d0

Create a ZFS volume to be used as a SCSI LUN.
```
target# zfs create -V 2g sanpool/vol1
```
Create a LUN for the ZFS volume.
```
target# stmfadm create-lu /dev/zvol/rdsk/sanpool/vol1
Logical unit created: 600144F0B5418B0000004DDAC7C10001
```
You can find the device path for the ZFS volume in the /dev/zvol/rdsk/pool-name/ directory.

Confirm that the LUN has been created.

target# stmfadm list-lu
LU Name: 600144F0B5418B0000004DDAC7C10001

Add the LUN view.
This command makes the LUN accessible to all systems.
```
target# stmfadm add-view 600144F0B5418B0000004DDAC7C10001
```
If you want to restrict the LUN view to specific systems, see How to Restrict LUN Access to Selected Systems.

Verify the LUN configuration.

target# stmfadm list-view -l 600144F0B5418B0000004DDAC7C10001
View Entry: 0
    Host group   : All
    Target group : All
    LUN          : 0

How to Create the iSCSI Target

This procedure assumes that you are logged in to the local system will contains the iSCSI target.

Enable the iSCSI target service.

target# svcadm enable -r svc:/network/iscsi/target:default

Confirm that the service is enabled.

target# svcs -l iscsi/target
fmri         svc:/network/iscsi/target:default
name         iscsi target
enabled      true
state        online
next_state   none
state_time   Mon May 23 14:48:59 2011
logfile      /var/svc/log/network-iscsi-target:default.log
restarter    svc:/system/svc/restarter:default
dependency   require_any/error svc:/milestone/network (online)
dependency   require_all/none svc:/system/stmf:default (online)

Create the iSCSI target.

target# itadm create-target
Target iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c039405 successfully created

Display the iSCSI target information.

target# itadm list-target -v
TARGET NAME                                                  STATE    SESSIONS 
iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c039405  online   0        
        alias:                  -
        auth:                   none (defaults)
        targetchapuser:         -
        targetchapsecret:       unset
        tpg-tags:               default

How to Configure an IB HCA for iSER

An InfiniBand (IB) Host Channel Adapter (HCA) is required to take full advantage of the iSCSI Extensions for RDMA (iSER) capabilities. To use iSER, you must configure the HCA on both the target and the initiator.

Become an administrator on the host (initiator) system.
Connect the HCA to an IB switch.
See the vendor documentation for details.
Configure the target and the initiator for the HCA.
The target and the initiator must be on the same subnet. This example uses ibd0 as the driver.
```
# ipadm create-addr ibd0
```

Configure the IP address and port combination for the HCA.

# ipadm create-addr -T static -a local=10.1.190.141/24 ibd0/v4addr

Verify the interface configuration.

# ipadm show-addr
ADDROBJ           TYPE     STATE        ADDR
lo0/v4            static   ok           127.0.0.1/8
e1000g0/_b        dhcp     ok           10.1.190.141/24
lo0/v6            static   ok           ::1/128
e1000g0/_a        addrconf ok           fe80::214:4fff:fe27:360c/10

Become an administrator on the target system and repeat steps 3-5 for all other HCA hosts on the network.
Verify connectivity on both the target and the initiator.
```
target# ping initiator-ip
initiator# ping target-ip
```

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.

Enable the iSCSI initiator service.

initiator# svcadm enable network/iscsi/initiator

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           10.80.227.189/24
lo0/v6            static   ok           ::1/128
e1000g0/_a        addrconf ok           fe80::214:4fff:fe27:360c/10
target# itadm list-target -v
TARGET NAME                                                  STATE    SESSIONS 
iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c039405  online   0        
        alias:                  -
        auth:                   none (defaults)
        targetchapuser:         -
        targetchapsecret:       unset
        tpg-tags:               default

Configure the target to be statically discovered.

initiator# iscsiadm add static-config iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c039405,
10.80.227.189

Review the static configuration information.

initiator# iscsiadm list static-config
Static Configuration Target: iqn.1986-03.com.sun:02:73d12edc-9bb9-cb44-efc4-c3b36c039405,
10.80.227.189:3260

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

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 10.80.227.189
```
- If you have configured a dynamically discovered (iSNS) target, configure the iSNS discovery method.
```
initiator# iscsiadm add isns-server 10.80.227.189
```
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
```
Reconfigure the /dev namespace to recognize the iSCSI disk, if necessary.
```
initiator# devfsadm -i iscsi
```

How to Remove Discovered iSCSI Targets

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 iSCSI target device has already been configured.

Become an administrator.
(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
```
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 10.0.0.1:3260
```
- Remove an iSCSI iSNS discovery entry.
  
  For example:
```
# iscsiadm remove isns-server 10.0.0.1:3205
```
- Remove a static iSCSI discovery entry.
  
  For example:
```
initiator# iscsiadm remove static-config eui.5000ABCD78945E2B,10.0.0.1
```
Note - If you attempt to disable or remove a discovery entry that has an associated logical unit (LUN) 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 LUN, unmount the file systems, and so on. Then, repeat the disable or remove operation.

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-ee3debe7b0c8'
itadm delete-target failed with error 16

Creating iSCSI Target Portal Groups

You can create a target portal group (TPG) to manage the discovery of multiple iSCSI and iSER targets. A TPG is a list of IP addresses to determine upon which interfaces a specific iSCSI target will listen.

A TPG contains IP addresses and TCP port numbers. To use this capability, you need to do the following:

Create a TPG as a list of ip-address:port specifiers by using the itadm create-tpg command.
Bind a specific iSCSI target to a TPG by using the itadm modify-target -t command.
When an iSCSI target is made active, an iSCSI listener is created for each IP address and port belonging to a TPG associated with that target.

A TPG is an efficient way to control which targets are discovered through specific ports. For example, you could restrict your iSCSI target so that it is available only through one specific IP address or only through a set of iSER-capable IP addresses.

Note - Do not confuse target portal groups with target groups. A target group is a list of SCSI target ports that are all treated the same when creating views. Creating a view can help you facilitate LUN mapping. Each view entry specifies a target group, as host group, and a LUN. For more information on Target Groups and LUN mapping, see Making SCSI Logical Units Available and stmfadm(1M).

To learn about static and iSNS target discovery, see Configuring Dynamic or Static Target Discovery. The iSCSI initiator uses the iscsiadm command to discover TPGs. For more information, see iscsiadm(1M) and itadm(1M).

Using TPGs with iSER

When you use the SendTargets discovery and iSER at the same time, a common convention is to use a TPG to associate a specific iSCSI target port with only iSER-capable IP addresses. For example, if a target system has four IP addresses, A, B, C, and D, and only addresses B and C are iSER-capable, then addresses B and C could be added to a TPG, and assigned to a target T.

An iSCSI initiator with both Ethernet and InfiniBand (IB) interfaces could use the SendTargets discovery method to discover the possible storage targets. Without the use of TPGs, the initiator might always prefer the use of the Ethernet interfaces over the IB interfaces. By associating target T only with the IB interfaces, the initiator correctly prefers using its IB-capable interface when connecting to target T.

How to Create a Target Portal Group for iSCSI Targets

You can create a target portal group (TPG) by providing a unique name, and a TPG Tag (ranging from 2–65535) is automatically generated. TPG Tag 1 is reserved for the default TPG that is used when you do not explicitly set a TPG on the target. The portal for the default TPG matches requests from all network interfaces on port 3260.

The following steps shows how to create two TPGs, TPGA and TPGB, that use port 8000 for the IP addresses in TPGB.

Become an administrator.
Create two TPGs.
```
target# itadm create-tpg TPGA 192.168.0.1 192.168.0.2
target# itadm create-tpg TPGB 192.168.0.2:8000 192.168.0.2:8000
```
Note - IPv4 portals are specified in dotted address notation (for example, 192.168.0.1). IPv6 portal addresses must be enclosed in square brackets.
Configure an existing iSCSI target to use the TPGs, TPGA and TPGB.
```
# itadm modify-target -t TPGA,TPGB eui.20387ab8943ef7548
```
Verify the TPGs that you created.
```
# itadm list-tpg -v
```
You can remove a TPG with the itadm delete-tpg command.

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 LUNs 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 LUN and then create a ZFS file system.

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

Review the iSCSI LUN 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 LUN under MPxIO control. Disks 1-4 are local disks.

You can create a ZFS storage pool and ZFS file systems on the iSCSI LUN.
```
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.

Making SCSI Logical Units Available

How to Make a Logical Unit Available to All Systems
How to Restrict LUN Access to Selected Systems

Simply registering a logical unit (LUN) with the STMF framework does not make it available to hosts (initiators) on the network. This section describes how to make LUNs visible to initiator hosts for the following configurations.

For iSCSI, Fibre Channel, and FCoE configurations, a LUN must be mapped before it can be accessed. You can choose one of the following methods, both of which use the stmfadm command:

Simple mapping – Exposes the LUN to all initiators through all the ports, using one command. Making LUNs available to all hosts uses this method.
Selective mapping– Enables you to specify the hosts that can access the LUN. Making LUNs available to selected hosts uses this method. This process includes the following steps:
1. Defining host groups – A host group is a name given to a set of hosts (initiators) that are allowed to access the same LUNs. This step is not needed if the same set of LUNs is visible to all the hosts, as in simple mapping.
2. Defining target groups – A target group is a name given to a set of target ports that export the same set of LUNs to the same set of host groups. This step is not needed if the same set of LUNs is visible to all the hosts, as in simple mapping.
3. Adding one or more views for each logical unit – Adding a view creates a bridge between the LUN and the host initiator. When an initiator from the host group logs in to a target port contained in the target group, the LUN is visible.

Note - Don't confuse a target group with a target portal group (TPG). A TPG is a list of IP addresses that an iSCSI target listens to. A TPG can help you restrict an iSCSI target so that it is available only through one specific IP address. For more information on target groups, see stmfadm(1M).

A view entry consists of four components: host group, target group, logical unit (LUN), and LUN identifier. Of these four components, only the LUN identifier is required. If the other components are omitted, the following default values are assumed:

If the host group is omitted, the all initiators value is assumed.
If the target group is omitted, the all targets value is assumed.
If the LUN is omitted, the system chooses a suitable LUN for the entry.

How to Make a Logical Unit Available to All Systems

This procedure makes a LUN available to all initiator hosts on a storage network.

Obtain the Global Unique Identification (GUID) number for the LUN.
```
# stmfadm list-lu -v
```
Add a view for the logical unit.
```
3 # stmfadm add-view GUID-number
```

How to Restrict LUN Access to Selected Systems

Use this procedure to restrict LUNs to selected hosts on a storage network. If you are using Fibre Channel ports, first identify the World Wide Names (WWN). Then, selectively map a logical unit number (LUN) to the ports on host-a, for example. A target group (targets-0) is also defined for a given set of target ports that export the same set of LUNs to the same host group.

For information about configuring a target group, see stmfadm(1M).

Become an administrator.

Identify the Fibre Channel (FC) port on the initiator.

initiator# fcinfo hba-port
HBA Port WWN: 210000e08b195dae
        Port Mode: Initiator
        Port ID: 0
        OS Device Name: /dev/cfg/c8
        Manufacturer: QLogic Corp.
        Model: 375-3108-xx
        Firmware Version: 03.03.28
        FCode/BIOS Version:  fcode: 1.13;
        Serial Number: not available
        Driver Name: qlc
        Driver Version: 20100408-3.01
        Type: unknown
        State: offline
        Supported Speeds: 1Gb 2Gb 
        Current Speed: not established 
        Node WWN: 200000e08b195dae
        NPIV Not Supported
.
.
.

Create a host group.

target# stmfadm create-hg host-a 210000e08b195dae 210100e08b395dae

Add the WWNs identified in the preceding output as members of the host group.
```
target# stmfadm add-hg-member -g host-a
```
Create a target group.
```
target# stmfadm create-tg targets-0
```
Specify the target group members by adding the target names.
Each SCSI target can be a member of only one target group.
```
target# stmfadm add-tg-member -g targets-0 wwn.guid-number
```
Identify the GUID number for the LUN.
```
target# stmfadm list-lu -v
```
Make the LUN available by adding a view entry, specifying the host group name and the LUN GUID number.
```
target# stmfadm add-view -h host-a -t targets-0 -n 1 guid-number
```

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