IBM Flex System V7000 Expansion Enclosure 4939H29 Manuale Utente

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Draft Document for Review January 29, 2013 12:52 pm
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IBM Flex System V7000 Storage Node Introduction and Implementation Guide
Commands, which are sent by the client and processed by the server, are put into the 
Command Descriptor Block (CDB). The server runs a command, and completion is indicated 
by a special signal alert. 
The major functions of iSCSI include encapsulation and the 
reliable delivery
 of CDB 
transactions between initiators and targets through the Internet Protocol network, especially 
over a potentially unreliable IP network.
The concepts of names and addresses have been 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 not only the iSCSI name of an iSCSI node, but also 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 Flex System V7000 Storage Node 
control canister represents an iSCSI node and provides statically allocated IP addresses.
Each iSCSI node, that is, an initiator or target, has a unique iSCSI Qualified Name (IQN), 
which can have a size of up to 255 bytes. The IQN is formed according to the rules adopted 
for Internet nodes. 
The iSCSI qualified name format is defined in RFC3720 and contains (in order) 
these elements: 
��
The string “
iqn
”.
��
A date code specifying the year and month in which the organization registered the 
domain or subdomain name used as the naming authority string.
��
The organizational naming authority string, which consists of a valid, reversed domain or a 
subdomain name.
��
Optionally, a colon (:), followed by a string of the assigning organization’s choosing, which 
must make each assigned iSCSI name unique.
For IBM Flex System V7000 Storage Node the IQN for its iSCSI target is specified as:
iqn.1986-03.com.ibm:2145.<clustername>.<nodename>
On a Windows server, the IQN, that is, the name for the iSCSI initiator, can be defined as:
iqn.1991-05.com.microsoft:<computer name>
The IQNs can be abbreviated by using a descriptive name, known as an 
alias
. An alias can 
be assigned to an initiator or a target. The alias is independent of the name and does not 
need to be unique. Because it is not unique, the alias must be used in a purely informational 
way. It cannot be used to specify a target at login or used during authentication. Both targets 
and initiators can have aliases.
An iSCSI name provides the correct identification of an iSCSI device irrespective of its 
physical location. Remember, the IQN is an 
identifier
, not an 
address