Dell PowerStore 5200T EMC PowerStore Host Configuration Guide - Page 32

Delayed ACK, Login Timeout, No-Op Interval, About this task, Steps, Example

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Delayed ACK For optimal traffic, it is recommended to disable Delayed ACK on ESXi. For optimal iSCSI traffic between the ESXi hosts and PowerStore, especially during periods of network congestion, it is recommended to disable Delayed ACK on ESXi. By disabling Delayed ACK, the ESXi host would send an ACK acknowledgment segment for every received data segment (rather than delaying the sending of ACK acknowledgment segments, while receiving a stream of TCP data segments). For information about the Delayed ACK parameter and how to disable it using the vSphere Client, See VMware Knowledge Article 1002598 (ESX/ESXi hosts might experience...). NOTE: The recommended method for configuring the Delayed ACK setting is per discovered iSCSI target. As a result, Delayed ACK can be disabled only for PowerStore iSCSI targets. Login Timeout Follow these steps to set the iSCSI login timeout. About this task When establishing an iSCSI session between the initiator and target, the login timeout setting controls how long the ESXi host attempts to log in to the iSCSI target before failing the login and retrying. The default setting for LoginTimeOut is five. For example, by default an iSCSI session ceases retries after 20 seconds (five times the LoginRetryMax setting, which is set by default to four). To optimize the iSCSI session behavior with PowerStore and to better handle periods of network disruptions, it is recommended to adjust LoginTimeOut to 30. The following steps describe how to adjust LoginTimeOut, using command line. Steps 1. Connect to the host as root. 2. Run the following command: esxcli iscsi adapter param set -A adapter_name -k LoginTimeout -v value_in_sec Example Replacing VMHBA number with the iSCSI vmhba: esxcli iscsi adapter param set -A vmhba66 -k LoginTimeout -v 30 No-Op Interval Follow these steps to set the iSCSI No-Op interval. About this task The noop iSCSI settings (NoopInterval and NoopTimout) are used to determine whether a path is dead, when it is not the active path. iSCSI passively discovers whether this path is dead using NoopTimout. This test is carried out on nonactive paths every NoopInterval, and if NoopTimout does not receive a response, the path is marked as DEAD. The default setting for NoopInterval is 10. To optimize the iSCSI session behavior with PowerStore, it is recommended to adjust NoopInterval to five. This adjustment would trigger an iSCSI path failover following a network disconnection before the command times out. The following steps describe how to adjust NoopInterval using command line: Steps 1. Connect to the host as root. 32 Host Configuration for VMware vSphere ESXi

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Delayed ACK
For optimal traffic, it is recommended to disable Delayed ACK on ESXi.
For optimal iSCSI traffic between the ESXi hosts and PowerStore, especially during periods of network congestion, it is
recommended to disable Delayed ACK on ESXi. By disabling Delayed ACK, the ESXi host would send an ACK acknowledgment
segment for every received data segment (rather than delaying the sending of ACK acknowledgment segments, while receiving
a stream of TCP data segments).
For information about the Delayed ACK parameter and how to disable it using the vSphere Client, See
VMware Knowledge
Article 1002598 (ESX/ESXi hosts might experience...)
.
NOTE:
The recommended method for configuring the Delayed ACK setting is per discovered iSCSI target. As a result,
Delayed ACK can be disabled only for PowerStore iSCSI targets.
Login Timeout
Follow these steps to set the iSCSI login timeout.
About this task
When establishing an iSCSI session between the initiator and target, the login timeout setting controls how long the ESXi host
attempts to log in to the iSCSI target before failing the login and retrying. The default setting for
LoginTimeOut
is five. For
example, by default an iSCSI session ceases retries after 20 seconds (five times the
LoginRetryMax
setting, which is set by
default to four).
To optimize the iSCSI session behavior with PowerStore and to better handle periods of network disruptions, it is recommended
to adjust
LoginTimeOut
to 30.
The following steps describe how to adjust
LoginTimeOut
, using command line.
Steps
1.
Connect to the host as
root
.
2.
Run the following command:
esxcli iscsi adapter param set -A adapter_name -k LoginTimeout -v value_in_sec
Example
Replacing VMHBA number with the iSCSI vmhba:
esxcli iscsi adapter param set -A vmhba66 -k LoginTimeout -v 30
No-Op Interval
Follow these steps to set the iSCSI No-Op interval.
About this task
The noop iSCSI settings (
NoopInterval
and
NoopTimout
) are used to determine whether a path is dead, when it is not the active
path. iSCSI passively discovers whether this path is dead using
NoopTimout
. This test is carried out on nonactive paths every
NoopInterval
, and if
NoopTimout
does not receive a response, the path is marked as DEAD.
The default setting for
NoopInterval
is 10. To optimize the iSCSI session behavior with PowerStore, it is recommended to
adjust
NoopInterval
to five. This adjustment would trigger an iSCSI path failover following a network disconnection before the
command times out.
The following steps describe how to adjust
NoopInterval
using command line:
Steps
1.
Connect to the host as
root
.
32
Host Configuration for VMware vSphere ESXi