A Storage Partition is a logical entity consisting of one or more Storage Subsystem logical drives that can be shared among hosts that are part of a host group or accessed by a single host. A Storage Partition is created when you define a collection of hosts (a host group) or a single host and then define a logical drive-to-logical unit number (LUN) mapping. This mapping allows you to define what host group or host will have access to a particular logical drive in your Storage Subsystem.
Storage Partitions are a premium feature of the storage management software and therefore must be enabled either by you or your storage vendor supplier. There is a maximum number of partitions that can be created on the Storage Subsystem depending on the premium feature that has been enabled. Benefits of partitioning include ease of management, amortization of costs, scalability, and flexibility.
There are three main steps to Storage Partitions configuration.
1 |
Create logical drives on your Storage Subsystem. During logical drive creation, you can specify one of two logical drive-to-LUN mapping settings: Default or None (map later).
For more information, see Creating a Logical Drive. |
2 | Define the host groups and hosts (and their associated host ports) for which you want to define specific logical drive-to-LUN mappings (your Topology). For more information, see Defining Storage Partitions Topology, below. |
3 |
Grant access to one or more logical drives to a defined host group or host. You do this by defining a specific logical drive-to-LUN
mapping using the following general steps: (1) Select a defined host group or host in the Topology View, (2) Select
the Define New Mappings option, (3) Select a logical drive that you want the host group or host to be able to access,
and (4) Select the logical unit number (LUN) you want the host group or host to use to access the logical drive.
For more information, see Defining Logical Drive-to-LUN Mappings, below. The following example shows that two host groups have been defined (host group Omaha and Kansas City) that have access to various logical drives. In this example, two partitions have been used. The first partition consists of logical drives Financial and Legal and it is accessed by the hosts in host group Kansas City using LUNs 4 and 2, respectively. The second partition consists of logical drives Engineering, Marketing, and H Resources and it is accessed by the hosts in host group Omaha using LUNs 5, 6, and 7, respectively. |
A Storage Partition Topology is a collection of topological elements (default host group, host group, host, and host port) shown as nodes in the Topology View of the Storage Partitions Definitions Window. You must define the various topological elements if you want to define specific logical drive-to-LUN mappings for host groups and/or hosts.
Note: Even if you are not planning to use Storage Partitions, you can still define your hosts and host ports that are connected to the particular Storage Subsystem and view the default logical drive-to-LUN mappings to determine which logical unit numbers are being used to access the logical drives in your Storage Subsystem.
A default host group is a standard node in the Topology View that designates all host groups, hosts, and host ports that: (1) do not have any specific logical drive-to-LUN mappings, and (2) share access to any logical drives that were automatically assigned default LUNs by the controller firmware during logical drive creation.
A host group is an optional topological element that you define if you want to designate a collection of hosts that will share access to the same logical drives. For more information, see Defining a Host Group.
A host is a computer that is attached to the Storage Subsystem and accesses various logical drives on the Storage Subsystem through its host ports. You can define a host as a separate entity or as part of a host group. You can define specific logical drive-to-LUN mappings to an individual host as well as have the host be part of a host group that shares access to one or more logical drives. For more information, see Defining a Host.
A host port is a physical connection on the host adapter that resides within a host. When the host adapter only
has one physical connection (host port), the terms host port and host adapter are synonymous.
The host ports are automatically discovered by the storage management software. A host port is the actual physical
connection that allows a host to gain access to the logical drives in the Storage Subsystem. Therefore, if you want to define
specific logical drive-to-LUN mappings for a particular host and create partitions, you must define its associated host
ports.
Initially, all discovered host ports belong to the default host group and have access to any logical drives that were
automatically assigned default LUNs by the controller firmware during logical drive creation. For more information, see
Defining a Host Port.
Any host port in the default host group can automatically access the following logical drives:
Example: In the following example, the logical drives in the Storage Subsystem Midwest have not been given specific logical drive-to-LUN mappings, therefore any hosts and their associated host ports in the default host group can request data from these logical drives. The LUNs are automatically assigned by the controller firmware.
A Storage Partitions topology is reconfigurable. You can:
Move a host from one host group into another host group
Delete a host group, host, or host port
Rename a host group, host, or host port
After you have defined your Storage Partitions topology, you can select a defined host group or host in the Topology View and select the Define New Mapping option to assign a specific logical drive and logical unit number (logical drive-to-LUN mapping). This designates that only the selected host group or host has access to the particular logical drive through the assigned LUN. For more information on the Define New Mapping option, see Defining a Logical Drive-to-LUN Mapping.
The storage management software manages the logical drive-to-LUN mappings. Host port requests for data issued for specific LUNs are routed to the appropriate logical drive by the controller firmware.
Important:
In the following example, three partitions have been configured.
The first partition consists of logical drive Financial. This logical drive is accessed by host KC-B using LUN 5. Even though host KC-B is part of the logical host group Kansas City, host KC-A cannot access this logical drive because the logical drive-to-LUN mapping was created with host KC-B rather than the host group Kansas City.
The second partition consists of logical drives Legal and Engineering. These logical drives are accessed by hosts KC-A and KC-B in host group Kansas City using LUNs 2 and 4, respectively.
The third partition consists of logical drives Marketing and H Resources. These logical drives are accessed by hosts Omaha
A and B in host group Omaha using LUNs 7 and 2, respectively.
In the following example, host Omaha has been granted access to logical drive Legal through LUN 6 through either of its host ports. Host KC has been granted access to logical drive Financial through LUN 6 and logical drive Engineering through LUN 7 through either of its host ports. Note that the same LUN (LUN 6 in this example) can be used for logical drive access for both hosts (Omaha and KC), because each host has its own LUN address space.
A logical drive-to-LUN mapping is reconfigurable. You can: