The following sections provide information about the major
concepts you need to understand to use the SAN Volume Controller.
Application servers
An application server is a host that is attached
to the SAN and that runs applications.
Call Home and inventory e-mail information SAN Volume Controller can
use Call Home e-mail and inventory information e-mail to provide data
and event notifications to you and to the IBM® Support
Center.
CIM agent
The Common Information Model (CIM) agent is a set of standards
that is developed by the Distributed Management Task Force (DMTF).
Clusters
All your configuration, monitoring, and service tasks are
performed at the cluster level. Therefore, after configuring your
cluster, you can take advantage of the virtualization and the advanced
features of the SAN Volume Controller.
Copy Services features
The SAN Volume Controller provides
Copy Services features that enable you
to copy virtual disks (VDisks).
Data migration SAN Volume Controller allows
you to migrate data across MDisks without interfering with any host
applications that are simultaneously accessing or writing data.
Storage systems and MDisks
The nodes in a cluster detect the storage exported by SAN-attached storage systems as
a number of disks, known as managed disks (MDisks). The SAN Volume Controller does
not attempt to provide recovery from physical disk failures within
a storage system.
An MDisk is usually, but not necessarily, a RAID array.
Host objects A host
system is a computer that is connected to the SAN Volume Controller through
either a fibre-channel interface or an IP network.
IBM System Storage Productivity Center TheIBM System Storage® Productivity Center (SSPC)
is an integrated hardware and software solution that provides a single
point of entry for managing SAN Volume Controller clusters, IBM System Storage DS8000® systems,
and other components of your data storage infrastructure.
I/O groups Each pair of nodes is known as an input/output
(I/O) group. An I/O group is defined during the cluster configuration
process.
MDisks A managed disk (MDisk) is a
logical disk (typically a RAID or partition thereof) that a storage system has
exported to the SAN fabric or LAN configuration to which the nodes
in the cluster are attached.
MDisk groups
A managed disk (MDisk) group is a collection of
MDisks that jointly contain all the data for a specified set of virtual
disks (VDisks).
Master console For SAN Volume Controller version
4.2.1 and earlier, the master console provides
a single point from which to manage the SAN Volume Controller nodes.The master console could
be purchased as a hardware product option (which includes the master console preinstalled
software) or as a software-only option.Although
it can no longer be purchased, the master console can
be upgraded to support clusters running the latest SAN Volume Controller software.
Nodes
A SAN Volume Controllernode is
a single processing unit within a SAN Volume Controller cluster.
Object naming
All objects in a cluster have names that are user-defined or system-generated.
SAN Volume Controller objects
The SAN Volume Controller solution
is based on a group of virtualization concepts. Before setting up
your SAN Volume Controller environment,
you should understand the concepts and the objects in the environment.
Port switches
The following sections provide examples of how to configure
your SAN in a small environment.
SAN Volume Controller The SAN Volume Controller combines
software and hardware into a comprehensive, modular appliance that
uses symmetric virtualization.
SCSI back-end layer
Ensure you are familiar with the small computer system
interface (SCSI) back-end support.
SCSI front-end layer
The small computer system interface (SCSI) front-end layer receives
input/output (I/O) commands sent from hosts and provides the SCSI-3 interface
to hosts. SCSI logical unit numbers (LUNs) are mapped to virtual disks (VDisks)
in this layer as well. Thus, the layer converts SCSI read commands and write
commands that are addressed to LUNs into commands that are addressed to specific
VDisks.
Secure Shell
Secure Shell (SSH) is a client-server network application. It is a communication vehicle between the host
system and the SAN Volume Controller command-line
interface (CLI).
SANs
A storage area network (SAN) is a pool of storage
systems in a SAN that are interconnected to the servers in an enterprise.
A SAN administrator is the person responsible for administering the
various resources on the SAN.
Space-efficient virtual disks
When you create a virtual disk (VDisk), you can designate
it as space-efficient. A space-efficient
VDisk has
a virtual capacity and a real capacity.
Storage Management Initiative Specification
The Storage Management Initiative Specification (SMI-S)
is a design specification of the Storage Management Initiative (SMI)
that is launched by the Storage Networking Industry Association (SNIA).
Storage pools
A storage pool is an aggregation of storage resources on
a storage area network (SAN) that a collection of hosts can use. These storage
resources can be from different vendors, and the host systems can also be
from different vendors. The pool can be split into virtual disks (VDisks)
that are visible to the host systems that use them. Therefore, VDisks can
use mixed back-end storage and provide a common way to manage SAN storage.
Storage systems A storage system,
or storage controller, is a device that coordinates and
controls the operation of one or more disk drives. A storage system synchronizes
the operation of the drives with the operation of the system as a
whole.
Switches
The SAN Volume Controller connects
to host systems and storage devices on
the storage area network (SAN) through switches. Switches from
different
vendors can be used together in a SAN Volume Controller configuration.
Redundant ac-power switch The redundant ac-power switch is
an optional feature that makes the SAN Volume Controller nodes
resilient to the failure of a single power circuit. The redundant ac-power switch is
not a replacement for an uninterruptible
power supply.
You must still use a uninterruptible
power supply for
each node.
Standard and persistent reserves The SCSI Reserve command
and the SCSI Persistent Reserve command are specified by the SCSI
standards. Servers can use these commands to prevent ports in other servers from accessing
the LUN.
Uninterruptible power supply The uninterruptible
power supply protects
a SAN Volume Controller node
against blackouts, brownouts, and power surges. The uninterruptible
power supply contains
a power sensor to monitor the supply and a battery to provide power
until an orderly shutdown of the system can be performed.
User roles
Each user of the SAN Volume Controller Console must
provide a user name and a password to sign on. Each
user also has an associated role such as monitor, copy operator, service,
administrator, or security administrator. These roles are defined
at the cluster level. For example, a user can perform the administrator
role for one cluster and perform the service role for another cluster.
Virtual disks
A virtual disk (VDisk) is a logical disk that
the cluster presents to the hosts.
Virtualization Virtualization is a concept that applies to many
areas of the information technology industry.
Vital product data Vital product data (VPD) is information that uniquely
records each hardware and licensed-internal-code element in the SAN Volume Controller nodes.