Dell Emulex Family of Adapters - Manual (Page 668)

Emulex Drivers for Windows User Manual P010077-01A Rev. A
3. Configuration
iSCSI Driver Configuration
668
Configuring LDTO and ETO on the Windows Server
LDTO and ETO values are configured using the Advanced tab of the Device Manager
Property page. Table 3-14 lists the default values of LDTO and ETO on the Windows
Server and the limits within which they can be configured.
Note: If the ETO is set to a number between 0 and 19, the driver assumes the value to
20 seconds internally. You will not see any modification to the registry.
To modify LDTO and ETO values, edit the driver parameters for the iscsi service:
1. Select the Emulex OneConnect iSCSI CNA in the Windows Device Manager under
Storage Controllers.
2. Right click and select Properties. The Device Manager Property page opens.
3. Select the Advanced tab and make the following changes:

LDTO = 25

ETO = 50
4. Reboot the system for the changes to take effect.
This sets the default value of LDTO to 25 seconds and the default value of ETO to 50
seconds. The settings are applied the next time the driver is loaded. You must reboot
the system (boot drivers) or disable the iSCSI driver and enable it again (non-boot
drivers) in Device Manager for the settings to take effect.
Error Handling Under MultiPath (MPIO) and Cluster
Configurations
In an MPIO or cluster configuration, fault tolerant software is present on the system in
addition to the iSCSI driver's default error handling scheme. Depending on the type of
failover configuration, the iSCSI driver's error handling parameter can be configured to
modify the timing characteristics of a failover operation.
If the iSCSI target is in Active-Active failover mode, the iSCSI driver can be configured
to report I/O errors as soon as they are detected by setting the iSCSI driver's LDTO and
ETO parameters to 0. This allows the failover software to trigger a path failover to an
active path or active node as quickly as possible.
If the iSCSI target is in Active-Standby failover mode, then the iSCSI driver must wait
for the target side failover operation to complete before reporting device unavailability
to the operating system. For such configurations, the driver's ETO must be set to the
amount of time the iSCSI target needs to complete its failover operation.
Table 3-14 LDTO and ETO Information on the Windows Server
Value Default Minimum Maximum
LDTO 20 sec 0 sec 3600 sec
ETO 90 sec 0 sec 3600 sec