You can use the management
GUI or the command-line interface to create a host cluster.
When you create a host cluster, you
can specify the hosts to include in the cluster. You can also create
an empty host cluster and add hosts later. If you select hosts to
add to the host cluster, all of the common private volume mappings
for the hosts become shared mappings for the host cluster. However,
you can also exclude specific volumes from being shared. The private
volume mappings are not shared with any other hosts in the host cluster.
A host can be a member of only one host cluster.
With shared mapping, volumes are
mapped on a host cluster basis. The volumes are shared by all of the
hosts in the host cluster, if there are no Small Computer System Interface
(SCSI) LUN conflicts among the hosts. Volumes that contain data that
is needed by other hosts are examples of a shared mapping.
Using the management GUI
To create a host
cluster, complete these steps:
- In the management GUI, select .
- On the Host Cluster page, select Create Host Cluster.
- On the Create Host Cluster page, enter
the name of the host cluster that you want to create.
- Select the available hosts to include within
the host cluster. By default, any volumes that are mapped to all the
selected hosts become a shared mapping for the host cluster, which
each of the hosts inherit. Any new volume mappings that are added
to the host cluster are inherited by each host in the host cluster.
You can also choose to create an empty host cluster to add individual
hosts later.
- Click Next.
- If you selected hosts to add to the host
cluster, you can exclude specific volumes that are already mapped
to these hosts. These volumes are retained as private mappings to
the individual hosts in the host cluster but do not become shared
mappings for the entire host cluster. New hosts that are added to
the host cluster do not inherit these volume mappings. Select any
volumes that you want to remain private mappings.
- If throttles are configured on any of the
selected hosts, the throttles must be removed to be included in the
host cluster. Throttles can be applied only to the host cluster and
not individual hosts within the cluster. If you choose not to remove
the throttles from the host, the host is excluded from the host cluster.
- Click Next.
- On the Summary page, verify the settings
and click Create Host Cluster.
Note: If you
selected hosts with volumes that have SCSI ID conflicts, the system
does not add these mappings to the host cluster. A SCSI LUN ID conflict
occurs when multiple hosts are mapped to the same volume but with
different SCSI IDs. In this case, a shared mapping is not created
because the system does not allow a volume to be mapped more than
once to the same host. The Summary page lists
all volumes that contain conflicts and the system retains these mappings
as private mappings to the original hosts.
Using the command-line interface
To create an empty host cluster by
using the command-line interface, enter the following command:
mkhostcluster -name name
where
name is the name of the new host cluster. To add hosts
to host cluster, you can use the
addhostclustermember command.
To create a host
cluster with host members, enter the following command:
mkhostcluster -name name -seedfromhost host_id_list | host_name_list
where
name is the name of the new host cluster
and
host_id_list or
host_name_list is either the ID or name of the hosts that you are adding to the
host cluster. By default any mappings that are associated with the
host become shared mappings for all the hosts in the host cluster.
If multiple hosts are added, any mappings that are in common among
the added hosts become shared mappings. Mappings that are not in common
remain private mappings to individual hosts.
To create a host cluster with host
members but to exclude a specific volume that is mapped to the host
from being shared in the host cluster, enter the following command:
mkhostcluster -name name -seedfromhost host_id_list | host_name_list
-ignoreseedvolume host_id_list | host_name_list
where
name is the name of the new
host cluster,
host_id_list or
host_name_list is either the ID or name of the hosts that you are adding to the
host cluster. If you want to exclude volumes from shared mappings
for the host cluster, use the
-ignoreseedvolume parameter to specify any volumes to remain private mappings. For
example, if you have a boot drive on a volume, you can exclude that
volume from being shared among all the host members in the cluster.