Chapter 1. Overview of the IBM Storwize V5000 Gen2 system 27
iSCSI is a block-level protocol that encapsulates SCSI commands into TCP/IP packets and
uses an existing IP network instead of requiring FC host bus adapters (HBAs) and a SAN
fabric infrastructure. Concepts of names and addresses are carefully separated in iSCSI.
An iSCSI name is a location-independent, permanent identifier for an iSCSI node. An iSCSI
node has one iSCSI name, which stays constant for the life of the node. The terms
initiator
name
and target name also refer to an iSCSI name.
An iSCSI address specifies the iSCSI name of an iSCSI node and a location of that node. The
address consists of a host name or IP address, a TCP port number (for the target), and the
iSCSI name of the node. An iSCSI node can have any number of addresses, which can
change at any time, particularly if they are assigned by way of Dynamic Host Configuration
Protocol (DHCP). An IBM Storwize V5000 node represents an iSCSI node and provides
statically allocated IP addresses.
Each iSCSI node, that is, an initiator or target, has a unique IQN, which can have a size of up
to 255 bytes. The IQN is formed according to the rules that were adopted for Internet nodes.
The IQNs can be abbreviated by using a descriptive name, which is known as an
alias. An
alias can be assigned to an initiator or a target.
For more information about configuring iSCSI, see Chapter 4, “Storage pools” on page 143.
1.6.11 Serial-attached SCSI
The serial-attached SCSI (SAS) standard is an alternative method of attaching hosts to the
IBM Storwize V5000 Gen2. The IBM Storwize V5000 Gen2 supports direct SAS host
attachment to address easy-to-use, affordable storage needs. Each SAS port device has a
worldwide unique 64-bit SAS address and operates at 12 Gbps.
1.6.12 Fibre Channel
Fibre Channel (FC) is the traditional method that is used for data center storage connectivity.
The IBM Storwize V5000 Gen2 supports FC connectivity at speeds of 4, 8, and 16 Gbps.
Fibre Channel Protocol is used to encapsulate SCSI commands over the FC network. Each
device in the network has a unique 64-bit worldwide port name (WWPN). The IBM Storwize
V5000 Gen2 supports FC connections directly to a host server or to external FC switched
fabrics.
1.7 IBM Storwize V5000 Gen2 features
In this section, we describe the features of the IBM Storwize V5000 Gen2. Different models
offer a different range of features. See Table 1-3 on page 6 for a comparison.
1.7.1 Mirrored volumes
IBM Storwize V5000 Gen2 provides a function that is called storage volume mirroring, which
enables a volume to have two physical copies. Each volume copy can belong to a different
storage pool and be on a different physical storage system to provide a high-availability (HA)
solution. Each mirrored copy can be either a generic, thin-provisioned, or compressed volume
copy.
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