failed to recv a PDU response, reconnecting

Error: "iscsid[3894]: discovery session to :3260 failed to recv a PDU response, reconnecting"

This is repeatedly seen in /var/log/messages

This is caused by the iSCSI discovery process. It is possible to change that behavior by adding 'continous=no' before the DiscoveryAddress in /etc/iscsi.conf.

Example:
continous=no
DiscoveryAddress=aaa.bbb.ccc.ddd

Then reboot the server.

The man page for iscsi.conf states the following for'continuous=yes|no' :

Specify whether discovery session should be kept alive or not after doing the discovery. Valid options are:

yes iSCSI initiator waits for IdleTimeout(60 seconds, default) to get a NOP-IN from target. If initiator gets a NOP-IN from tar get during IdleTimeout then initiator replies with NOP-OUT. But if initiator does not get a NOP-IN from target during Idle ttimeout then it sends NOP-OUT and expects NOP-IN response from target within PingTimeout(5 seconds, default). If target does not respond within PingTimeout then initiator assumes the connection has been inadvertently broken, drops the current discovery session and attempts to establish a new discovery session.

no iSCSI initiator closes the connection and will not attempt to establish a new one.