VMware has become aware of an where ESXi 5.0 attempts to connect to all configured or known targets from all configured software iSCSI portals. If a connection fails, ESXi 5.0 retries the connection 9 times. This can lead to a lengthy iSCSI discovery process, which increases the amount of time it takes to boot an ESXi 5.0 host.
To minimize the amount of time the boot process spends discovering iSCSI targets, you can reduce the number of network portals and the number of targets.
For details on this issue please refer to the Knowledgebase article: ESXi 5.x boot delays when configured for Software iSCSI (2007108).