Configuring iSCSI Multipath
Revised: April 27, 2011, OL-20458-02
This chapter describes how to configure iSCSI multipath for multiple routes between a server and its storage devices.
This chapter includes the following topics:
•Information About iSCSI Multipath
•Guidelines and Limitations
•Prerequisites
•Default Settings
•Configuring a Port Profile for iSCSI Multipath
•Additional References
•Feature History for iSCSI Multipath
Information About iSCSI Multipath
The iSCSI multipath feature sets up multiple routes between a server and its storage devices for maintaining a constant connection and balancing the traffic load. The multipathing software handles all input and output requests and passes them through on the best possible path. Traffic from host servers is transported to shared storage using the iSCSI protocol that packages SCSI commands into iSCSI packets and transmits them on the Ethernet network.
If a path or any component along the path fails, the server selects another of the available paths.
Guidelines and Limitations
The following are guidelines and limitations for the iSCSI multipath feature.
•The port profile used for iSCSI multipath must be an access port profile. It cannot be a trunk port profile.
•The following are required:
–A system VLAN created on the Cisco Nexus 1000V.
–One of the uplink ports must already have this VLAN in its system VLAN range.
–A host configured with one port channel that includes two or more physical NICs.
–VMware kernel NICs configured to access the SAN external storage are required.
•A Vmware Kernel NIC can only be pinned or assigned to one physical NIC.
•A physical NIC can have multiple VMware Kernel NICs pinned or assigned to it.
Prerequisites
The iSCSI Multipath feature has the following prerequisites.
•You must understand VMware iSCSI SAN storage virtualization.
•You must know how to set up the iSCSI Initiator software on your VMware ESX/ESXi host.
•The host is already functioning with the VMware ESX 4.0.1 Update 01 software release.
•You must understand iSCSI multipathing and path failover.
Default Settings
Table 13-1 lists the default settings in the iSCSI Multipath configuration.
Table 13-1 iSCSI Multipath Defaults
|
|
Type (port-profile) |
vEthernet |
Description (port-profile) |
None |
VMware port group name (port-profile) |
The name of the port profile |
Switchport mode (port-profile) |
Access |
State (port-profile) |
Disabled |
Configuring a Port Profile for iSCSI Multipath
Use this section to configure communication multipathing between hosts and targets over iSCSI protocol by assigning the vEthernet interface to an iSCSI multipath port profile configured with a system VLAN.
BEFORE YOU BEGIN
Before starting the procedures in this section you must know or do the following.
•You have already configured the host with one port channel that includes two or more physical NICs.
•You have already created VMware kernel NICs to access the SAN external storage.
•A Vmware Kernel NIC can only be pinned or assigned to one physical NIC.
•A physical NIC can have multiple VMware Kernel NICs pinned or assigned to it.
•Multipathing must be configured on the interface by using this procedue to create an iSCSI multipath port profile and then assigning the interface to it.
•You are logged in to the CLI in EXEC mode.
•You know the VLAN ID for the VLAN you are adding to this iSCSI multipath port profile.
–The VLAN must already be created on the Cisco Nexus 1000V.
–The VLAN that you assign to this iSCSI multipath port profile must be a system VLAN.
–One of the uplink ports must already have this VLAN in its system VLAN range.
•The port profile must be an access port profile. It cannot be a trunk port profile. This procedure includes steps to configure the port profile as an access port profile.
SUMMARY STEPS
1. config t
2. port-profile type vethernetname
3. vmware port-group [name]
4. switchport mode access
5. switchport access vlan vlanID
6. no shutdown
7. (Optional) system vlan vlanID
8. capability iscsi-multipath
9. state enabled
10. (Optional) show port-profile name
11. (Optional) copy running-config startup-config
DETAILED STEPS
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|
|
Step 1 |
config t Example: n1000v# config t n1000v(config)# |
Places you in the CLI Global Configuration mode. |
Step 2 |
port-profile type vethernet name
n1000v(config)# port-profile type vethernet VMK-port-profile n1000v(config-port-prof)# |
Places you into the CLI Port Profile Configuration mode for the specified port profile. •type: Defines the port-profile as Ethernet or vEthernet type. Once configured, this setting cannot be changed. The default is vEthernet type. Note If a port profile is configured as an Ethernet type, then it cannot be used to configure VMware virtual ports. •name: The port profile name can be up to 80 characters and must be unique for each port profile on the Cisco Nexus 1000V. |
Step 3 |
description profiledescription
Example: n1000v(config-port-prof)# description "Port Profile for iSCSI multipath" n1000v(config-port-prof)# |
Adds a description to the port profile. This description is automatically pushed to the vCenter Server. profile description: up to 80 ASCII characters Note If the description includes spaces, it must be surrounded by quotations. |
Step 4 |
vmware port-group [name]
n1000v(config-port-prof)# vmware port-group VMK-port-profile n1000v(config-port-prof)# |
Designates the port-profile as a VMware port group. The port profile is mapped to a VMware port group of the same name. When a vCenter Server connection is established, the port group created in Cisco Nexus 1000V is then distributed to the virtual switch on the vCenter Server. name: The Vmware port group name.If you want to map the port profile to a different port group name, use the alternate name. |
Step 5 |
switchport mode access ]
n1000v(config-port-prof)# switchport mode access n1000v(config-port-prof)# |
Designates that the interfaces are switch access ports (the default). |
Step 6 |
switchport access vlan vlanID
n1000v(config-port-prof)# switchport access vlan 254 n1000v(config-port-prof)# |
Assigns the system VLAN ID to the access port for this port profile. Note The VLAN assigned to this iSCSI port profile must be a system VLAN. |
Step 7 |
no shutdown
n1000v(config-port-prof)# no shutdown n1000v(config-port-prof)# |
Administratively enables all ports in the profile. |
Step 8 |
system vlan vlanID Example: n1000v(config-port-prof)# system vlan 254 n1000v(config-port-prof)# |
Adds the system VLAN to this port profile. This ensures that, when the host is added for the first time or rebooted later, the VEM will be able to reach the VSM. One of the uplink ports must have this VLAN in its system VLAN range. |
Step 9 |
capability iscsi-multipath
n1000v(config-port-prof)# capability iscsi-multipath n1000v(config-port-prof)# |
Allows the port to be used for iSCSI multipathing. In vCenter Server, the iSCSI Multipath port profile must be selected and assigned to the VM kernel NIC port. |
Step 10 |
state enabled
n1000v(config-port-prof)# state enabled n1000v(config-port-prof)# |
Enables the port profile. The configuration for this port profile is applied to the assigned ports, and the port group is created in the VMware vSwitch on the vCenter Server. |
Step 11 |
show port-profile name name Example: n1000v(config-port-prof)# show port-profile name multipath-profile n1000v(config-port-prof)# |
(Optional) Displays the current configuration for the port profile. |
Step 12 |
copy running-config startup-config Example: n1000v(config-port-prof)# copy running-config startup-config |
(Optional) Saves the running configuration persistently through reboots and restarts by copying it to the startup configuration. |
Additional References
For additional information related to implementing iSCSI Multipath, see the following sections:
•Related Documents
•Standards
Related Documents
|
|
VMware SAN Configuration |
VMware SAN Configuration Guide |
Port Profile Configuration |
Cisco Nexus 1000V Port Profile Configuration Guide, Release 4.0(4)SV1(2) |
Interface Configuration |
Cisco Nexus 1000V Interface Configuration Guide, Release 4.0(4)SV1(2) |
Complete command syntax, command modes, command history, defaults, usage guidelines, and examples for all Cisco Nexus 1000V commands. |
Cisco Nexus 1000V Command Reference, Release 4.0(4)SV1(2) |
Standards
|
|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
— |
Feature History for iSCSI Multipath
Table 13-2 lists the release history for the iSCSI Multipath feature.
Table 13-2 Feature History for iSCSI Multipath
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|
|
iSCSI Multipath |
4.0(4)SV1(2) |
Th iSCSI Multipath feature was added. |
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