HP LeftHand P4000 Virtual SAN Appliance Software - Manual (Page 230)

19 iSCSI and the HP P4000 SAN Solution
The SAN/iQ software uses the iSCSI protocol to let servers access volumes. For fault tolerance
and improved performance, use a VIP and iSCSI load balancing when configuring server access
to volumes.
The following concepts are important when setting up clusters and servers in the SAN/iQ software:
•
“Virtual IP addresses” (page 230)
•
“iSNS server” (page 230)
•
“iSCSI load balancing” (page 231)
•
“Authentication (CHAP)” (page 231)
•
“iSCSI and CHAP terminology” (page 232)
•
“About HP DSM for MPIO” (page 234)
Number of iSCSI sessions
For information about the recommended maximum number of iSCSI sessions that can be created
in a management group, see
“Configuration Summary overview” (page 109) .
Virtual IP addresses
A virtual IP (VIP) address is a highly available IP address which ensures that if a storage system in
a cluster becomes unavailable, servers can still access a volume through the other storage systems
in the cluster.
Your servers use the VIP to discover volumes on the SAN. The SAN uses the iqn from the iSCSI
initiator to associate volumes with the server.
A VIP is required for a fault tolerant iSCSI cluster configuration, using VIP load balancing or the
HP DSM for MPIO.
When using a VIP, one storage system in the cluster hosts the VIP. All I/O goes through the VIP
host. You can determine which storage system hosts the VIP by selecting the cluster, then clicking
the iSCSI tab.
Requirements for using a virtual IP address
•
For standard clusters (not multi-site clusters), storage systems occupying the same cluster must
be in the same subnet address range as the VIP.
•
The VIP must be routable regardless of which storage system it is assigned to.
•
iSCSI servers must be able to ping the VIP when it is enabled in a cluster.
•
The VIP address must be different than any storage system IPs on the network.
•
The VIP address must be a static IP address reserved for this purpose.
•
All iSCSI initiators must be configured to connect to the VIP address for the iSCSI failover to
work properly.
iSNS server
An iSNS server simplifies the discovery of iSCSI targets on multiple clusters on a network. If you
use an iSNS server, configure your cluster to register the iSCSI target with the iSNS server. You
can use up to 3 iSNS servers, but none are required.
230 iSCSI and the HP P4000 SAN Solution