Host Groups

In this topic:

About host groups

Creating host groups

Adding hosts to existing groups

Removing hosts from groups

Deleting groups

Viewing group details

Also see:

Quality of Service

Charge Back

About Host Groups

Hosts can be grouped to allow operations to be performed simultaneously on the entire group. Virtual disks can be served to or unserved from the group simultaneously with a single command. Host groups are useful when serving the same virtual disks to multiple hosts.

Any number of host groups can be created with an unlimited number of members, but any host can only be a member of one host group.

Host groups also provide a way to create a logical grouping of hosts so that I/O traffic can be managed through Quality of Service settings. The demands of different applications can be better accommodated by grouping hosts with similar data transfer requirements; such as applications that issue many small data transfer operations (such as database applications) or few large data transfer operations (such as back-up applications). See Quality of Service for more information.

The Charge Back feature allows IT organizations to track and measure I/O statistics per host group. This feature allows I/O resources to be "metered" so that organizations can determine the resources used per host group and charge back the costs of storage-related expenses. See Charge Back for more information.

Serving Virtual Disks

Individual virtual disks or virtual disk groups can be served to host groups. Serving virtual disks to host groups is performed in the same manner as serving virtual disks to individual hosts. The Quick Serve feature is also supported. See Serving Virtual Disks for more information.

Unserving Virtual Disks

All virtual disks can be unserved from a host group at once using a single command, Unserve All Virtual Disks. To unserve a subset of the complete set of individual and virtual disks groups that are served to the group, the virtual disks must be unserved from each host in the group. See Serving Virtual Disks for more information.

Creating Host Groups

1. In the Hosts Panel or Hosts List, right-click on a host, point to Add to Group and then select Create Group.
2. The Create Host Group dialog box opens. A default name is entered In the name field. Change the group name and enter a description of the group if necessary.
3. From the list, select one or more hosts to add to the group.

   (Alternatively, create hosts on-the-fly to add to the group by clicking the Register Host link on this page.)

4. Click Create.

After the group is created:

• The group appears everywhere that individual hosts would appear in the management console.
• A Host Group details page is created for the group.

Adding Hosts to Existing Groups

Virtual disks that have already been served to a host group, will not automatically be served to a new host added to the group at a later time. In order to include previously served virtual disks, the virtual disks must be served to the new host manually.

To add a host:

• In the Hosts Panel or Hosts List, right-click on a host, point to Add to Group and then select the group.

  Alternatively, right-click on the host group and select Add Hosts.

Removing Hosts from Groups

• In the Hosts Panel or Hosts List, right-click on the host to remove and select Remove from Group.

Deleting Groups

Deleting a host group does not delete the hosts that are members of the group.

Use caution when deleting a host group that ever had Charge Back enabled. Recorded data for a host group cannot be reported after that host group is deleted from the configuration. Do not delete host groups unless recorded data is no longer needed.

To delete the group:

• In the Hosts Panel or Hosts List, right-click on the group to delete and select Delete.

Viewing Group Details

Each host group has a details page with pertinent information for that group.

To open the details page for a host group:

• In the Hosts Panel or Hosts List, right-click on the host group and select View Details.

  You can also double-click the host group to open the details page.

When the Host Group Details page is active, the Host Group Actions tab appears in the Ribbon to perform actions on the group.

At the top of the page:

• Group name and description can be changed at the top of the page by clicking Edit. When changes are made, click Done.

Tabs:

Information is organized under tabs (described below). Click on a tab to view the information.

Host Group Detail Page
Settings tab	Quality of Service settings, see Quality of Service. Maximum data transferred per second Maximum I/O operations per second Charge back setting to record I/O statistics for the host group, see Charge Back.
Hosts tab	Displays basic information for all hosts in the group, such as name, description, state, operating system type, and multipath and ALUA settings.
Performance tab	Displays real-time performance measurements for the group. See Live Performance.
Events tab	Lists events for the group. Click an event in the list to view details in the Message Text area at the bottom of the tab. See Event Log and Alerts.