Host configuration
Using a NIC versus using an iSCSI HBA
All hosts in an IP SAN can utilize a standard IEEE NIC; however, an iSCSI HBA should be used
for overall better performance or if booting from the SAN.
A host can have one or more 10/100/1000 NICs or 1 Gb/s iSCSI HBAs. If the customer has a
host application with substantial I/O requirements, then an iSCSI HBA should be considered. As
a general rule, the iSCSI HBA will perform better than a standard 10/100/1000 NIC due to the
iSCSI HBA’s TOE, which handles the processing of the TCP/IP frames of the iSCSI packets. For
hosts that do not have a TOE, the host’s CPU(s) will process these frames, potentially impacting
performance. A single NIC or iSCSI HBA is required for the iSCSI solution; however, two NICs or
HBAs are strongly recommended with the use of PowerPath® or other host failover software to
ensure host connectivity through path failures. PowerPath can also provide load balancing, finetuning
and balancing the I/O loads across all available paths between the host and the storage
system.