HP StoreVirtual 4000 Storage - Manual (Page 238)

19 HP StoreVirtual Storage using iSCSI and Fibre Channel
iSCSI and HP StoreVirtual Storage
The LeftHand OS 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.
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 110) .
VIPs
A VIP 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 StoreVirtual DSM for Microsoft 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.
iSCSI load balancing
Use iSCSI load balancing to improve iSCSI performance and scalability by distributing iSCSI
sessions for different volumes evenly across storage systems in a cluster. iSCSI load balancing uses
iSCSI Login-Redirect. Only initiators that support Login-Redirect should be used.
When using VIP and load balancing, one iSCSI session acts as the gateway session. All I/O goes
through this iSCSI session. You can determine which iSCSI session is the gateway by selecting the
cluster, then clicking the iSCSI Sessions tab. The Gateway Connection column displays the IP
address of the storage system hosting the load balancing iSCSI session.
Configure iSCSI load balancing when setting up servers. See “Adding an iSCSI server connection”
(page 204) .
238 HP StoreVirtual Storage using iSCSI and Fibre Channel