I've had a few questions recently about some of the iSCSI configuration parameters found in the Advanced Settings.
When iSCSI establishes a session between initiator and target, it has to login to the target. It will try to login for a period of LoginTimeout. If that exceeds, the login fails.
When iSCSI finishes a session between initiator and target, it has to logout of the target. It will try to logout for a period of LogoutTimeout. If that exceeds, the logout fails.
The other options relate to how we determine a DEAD PATH:
- RecoveryTimeout is used to determine how long we should wait before placing a path into a DEAD_STATE when the path was active, but now no PDUs are being sent or received. Realistically it’s a bit longer than that, as other considerations are taken into account as well.
- The noop settings are used to determine if a path is dead, when it is not the active path. iSCSI will passively discover if this path is dead by using the noop timeout. This test is carried out on non-active paths every NoopInterval, and if a response isn’t received by NoopTimeout, the path is marked as DEAD.
Unless you wanted faster failover times, you probably wouldn't ever need to edit these. But be careful because if you have paths failing too quickly and then recovering, you could have LUNs/devices moving unnecessarily between array controller targets which could lead to path thrashing.
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