Dell PowerStore 7000T EMC PowerStore Host Configuration Guide - Page 18

Pre-Requisites, Jumbo Frames, Delayed ACK, Login Timeout

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NOTE: Be sure to review iSCSI SAN Guidelines before you proceed. Pre-Requisites Before configuring iSCSI, the following pre-requisites should be met: • Follow the VMware recommendations for installation and setup of the appropriate NIC/iSCSI HBA for your system. • It is recommended to install the latest driver version (patch), as described in the VMware support site for each specific NIC/iSCSI HBA. • Refer to the E-Lab interoperability Navigator (https://elabnavigator.emc.com) for supported NIC/iSCSI HBA models and drivers. Jumbo Frames Configure end-to-end Jumbo Frames for optimal performance. When using iSCSI with ESXi hosts and PowerStore, it is recommended to configure end-to-end Jumbo Frames (MTU=9000) for optimal performance. With Jumbo Frames, Ethernet frames are set to be larger than 1500 bytes (up to 9000 bytes). NOTE: When using Jumbo Frames, make sure that all ports (ESXi server, switch/es and storage) are configured with the correct MTU value. With VMware ESXi, the correct MTU size must be set on the virtual switch as well. For further details on configuring Jumbo Frames with iSCSI on ESXi, refer to VMware KB article 1007654 on the VMware website (https://kb.vmware.com/kb/1007654). 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 further details on the Delayed ACK parameter and how to disable it using the vSphere Client, refer to VMware KB article 1002598 on the VMware website (https://kb.vmware.com/kb/1002598). NOTE: The recommended method for configuring the Delayed ACK setting is per discovered iSCSI target. This allows to disable Delayed ACK 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 5. For example, by default an iSCSI session ceases retries after 20 seconds (5 times the LoginRetryMax setting, which is set by default to 4). 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 ESXi host as root. 2. Run the following command: esxcli iscsi adapter param set -A adapter_name -k LoginTimeout -v value_in_sec Example For example: esxcli iscsi adapter param set -A vmhba64 -k LoginTimeout -v 30 18 Host Configuration for VMware vSphere ESXi

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NOTE:
Be sure to review
iSCSI SAN Guidelines
before you proceed.
Pre-Requisites
Before configuring iSCSI, the following pre-requisites should be met:
•
Follow the VMware recommendations for installation and setup of the appropriate NIC/iSCSI HBA for your system.
•
It is recommended to install the latest driver version (patch), as described in the VMware support site for each specific NIC/iSCSI
HBA.
•
Refer to the E-Lab interoperability Navigator (
) for supported NIC/iSCSI HBA models and drivers.
Jumbo Frames
Configure end-to-end Jumbo Frames for optimal performance.
When using iSCSI with ESXi hosts and PowerStore, it is recommended to configure end-to-end Jumbo Frames (MTU=9000) for optimal
performance. With Jumbo Frames, Ethernet frames are set to be larger than 1500 bytes (up to 9000 bytes).
NOTE:
When using Jumbo Frames, make sure that all ports (ESXi server, switch/es and storage) are configured with
the correct MTU value. With VMware ESXi, the correct MTU size must be set on the virtual switch as well.
For further details on configuring Jumbo Frames with iSCSI on ESXi, refer to VMware KB article 1007654 on the VMware website
(
).
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 further details on the Delayed ACK parameter and how to disable it using the vSphere Client, refer to VMware KB article 1002598 on
the VMware website (
).
NOTE:
The recommended method for configuring the Delayed ACK setting is per discovered iSCSI target. This allows to
disable Delayed ACK 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 5. For example, by default an
iSCSI session ceases retries after 20 seconds (5 times the
LoginRetryMax
setting, which is set by default to 4).
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 ESXi host as
root
.
2.
Run the following command:
esxcli iscsi adapter param set -A adapter_name -k LoginTimeout -v value_in_sec
Example
For example:
esxcli iscsi adapter param set -A vmhba64 -k LoginTimeout -v 30
18
Host Configuration for VMware vSphere ESXi