The SAN Volume Controller combines
software and hardware into a comprehensive, modular appliance that
uses symmetric virtualization.
Symmetric
virtualization is achieved by creating a pool of managed disks (MDisks)
from the attached storage systems. Those storage systems are then
mapped to a set of virtual disks (VDisks) for use by attached host
systems. System administrators can view and access a common pool of
storage on the storage area network (SAN). This functionality helps
administrators to use storage resources more efficiently and provides
a common base for advanced functions.
A SAN is a high-speed fibre-channel network
that connects host systems and storage devices. In a SAN, a host system
can be connected to a storage device across the network. The connections
are made through units such as routers and switches. The area of the
network that contains these units is known as the fabric of
the network.
SAN Volume Controller software
The
SAN Volume Controller software
performs the following functions for the host systems that attach
to
SAN Volume Controller:
- Creates a single pool of storage
- Provides logical unit virtualization
- Manages logical volumes
- Mirrors logical volumes
The SAN Volume Controller also
provides the following functions:
- Large scalable cache
- Copy Services
- IBM FlashCopy® (point-in-time copy)
- Metro
Mirror (synchronous
copy)
- Global Mirror (asynchronous
copy)
- Data migration
- Space management
- Mapping that is based on desired performance characteristics
- Metering of service quality
- Space-efficient logical volumes (thin provisioning)
SAN Volume Controller hardware
Each SAN Volume Controller node
is an individual server in a SAN Volume Controller cluster
on which the SAN Volume Controller software
runs.
The nodes are always installed in pairs,
with a minimum of one and a maximum of four pairs of nodes constituting
a cluster. Each pair of nodes is known as an I/O group.
All I/O operations that are managed by the nodes in an I/O group are
cached on both nodes.
Note: I/O groups take the storage that is presented to the SAN by
the storage systems as MDisks and translates the storage into logical
disks, known as VDisks, that are used by applications on the hosts.
A node resides in only one I/O group and provides access to the VDisks
in that I/O group.
The following
nodes are supported in
SAN Volume Controller 5.1:
- The new SAN Volume Controller 2145-CF8 node
is available for purchase, with up to four of the optional solid-state drives (SSDs).
- The SAN Volume Controller 2145-8A4 node
remains available for purchase.
- The SAN Volume Controller 2145-8G4 node
is no longer available for purchase, but remains supported in SAN Volume Controller 5.1.
- The SAN Volume Controller 2145-8F4 node
is no longer available for purchase, but remains supported in SAN Volume Controller 5.1.
- The SAN Volume Controller 2145-8F2 node
is no longer available for purchase, but remains supported in SAN Volume Controller 5.1.
Attention: The SAN
Volume Controller 2145-4F2 node
is supported only in SAN Volume Controller 4.3.1
and earlier releases.