Follow these
configuration details for iSCSI host connections.
Attach the system to Internet Small
Computer Systems Interface (iSCSI) hosts by using the Ethernet ports on the systems.
Note: The system supports SAN devices that bridge iSCSI connections into a Fibre
Channel network.
iSCSI connections route from hosts to the systems over the LAN. Follow these configuration rules:
- There is no SLP support for discovery.
- Header and data digest support is provided only if the initiator is configured to
negotiate.
- Only one connection per session is supported.
- Only ErrorRecoveryLevel 0 (session restart) is supported.
iSCSI hosts connect to the system through the node-port IP addresses. During node failure, in
addition to node-port IP addresses, the iSCSI name, and iSCSI alias for the failed node are also
transferred to the partner node. After the failed node recovers, the node-port IP address and the
iSCSI name and alias are returned to the original node.
Note: The 100 Gbps adapter supports iSCSI. However, the
performance is limited 25 Gbps per port.
IP requirements for iSCSI
IP addresses are used to discover storage volumes and to use I/O to access the volumes. Node
iSCSI IP addresses are also used to access a remote Internet Storage Name Service (iSNS) server, if
configured.
- Each node Ethernet port can be configured on the same subnet with the same gateway, or you can
have each Ethernet port on separate subnets and use different gateways.
- If you are configuring a system to use node Ethernet ports 1 and 2 for iSCSI
I/O, ensure that the overall configuration also meets the system IP requirements that are listed
previously.
- To help ensure iSCSI IP failover operations, nodes in the same I/O group must be connected to
the same physical segments on the same node ports. However, you can
configure node Ethernet ports in different I/O groups to use different subnets and different
gateways.
You can configure iSNS to facilitate scalable configuration and management of iSCSI storage
devices. Currently, you can have only one type of protocol that is used by
the iSNS server at a time: either IPv4 or IPv6. For example, if you try to configure an IPv6 iSNS IP
address when you already configured an IPv4 iSNS IP address, the new IPv6 IP address becomes the
iSNS IP address. The old IP address can no longer be used for iSNS function.
iSCSI authentication
iSCSI supports two types of authentication through the Challenge Handshake Authentication
Protocol (CHAP):
- Unidirectional (one-way) authentication: The iSCSI target authenticates the iSCSI initiators.
- Bidirectional (two-way) authentication: The iSCSI target and the iSCSI initiators authenticate
each other.
Attention: With the iSCSI initiator, you can set two passwords: one for discovery and
another for iSCSI session I/O. However, the system requires that both passwords for each type of
authentication are the same. That is, two identical passwords for unidirectional (one-way) CHAP, and two identical
passwords for bidirectional (two-way) CHAP that are different from those passwords for unidirectional (one-way)
CHAP.
Host mapping
Use this information for specific iSCSI host mapping information. For additional general host
mapping information, see Ethernet connectivity.
iSCSI hosts that have a multipath driver that is installed can be moved in a
nondisruptive manner.
For more information about host mapping, see Host mapping.
iSCSI protocol supported session parameters
The following Ethernet session parameters are supported:
initial_r2t = 1
immediate_data = 0
max_connections = 1
Max_recv_segment_data_length = 32k
max_xmit_data_length = 32k
max_burst_length = 32k
first_burst_length = 32k
default_wait_time = 2
default_retain_time = 20
max_outstanding_r2t = 1
data_pdu_inorder = 1
data_sequence_inorder = 1
error_recovery_level = 0
header_digest = CRC32C,None
data_digest = CRC32C,None
ofmarker = 0
ifmarker = 0
ofmarkint = 2048
ifmarkint = 2048