Home > Storage > PowerMax and VMAX > Storage Admin > iSCSI Implementation Guide for Dell EMC Storage Arrays Running PowerMaxOS > Enable jumbo frames on iSCSI NICs if supported on network
Jumbo frames have shown a boost in iSCSI performance for small block reads and writes by as much as 20%. Jumbo frames do not provide as much benefit for iSCSI performance for larger block sizes (>64K). Always configure Jumbo Frames according to the NIC manufacturer instructions. Configure Jumbo Frames end-to-end on the network, with the smallest setting governing the end-to-end packet size. Enabling jumbo frames and Flow Control on the host NICs depends on the network configuration. If these features are not enabled on the network, then enabling them for the host NICs will provide no benefit. Before enabling these features on the host NICs, consult with the local network administrators and see if Jumbo Frames has been enabled on the network.
Examine jumbo frame settings on iSCSI NICs:
PS C:\> get-netadapteradvancedproperty –name SAN* -displayname "Jumbo Packet","Flow Control" | ft –property Name, Displayname, Displayvalue, validdisplayvalues -AutoSize
Name Displayname Displayvalue validdisplayvalues
---- ----------- ------------ ------------------
SAN1 Flow Control Rx & Tx Enabled {Disabled, Tx Enabled, Rx Enabled, Rx & Tx Enabled} <--- Flow control enabled
SAN1 Jumbo Packet Disabled {Disabled, 4088 Bytes, 9014 Bytes} <--- Jumbo Frames disabled
SAN2 Flow Control Rx & Tx Enabled {Disabled, Tx Enabled, Rx Enabled, Rx & Tx Enabled}
SAN2 Jumbo Packet Disabled {Disabled, 4088 Bytes, 9014 Bytes}
Enable jumbo frames on iSCSI NICs.
PS C:\> set-netadapteradvancedproperty -name SAN* -displayname "Jumbo Packet" -DisplayValue "9014 Bytes"
Verify that jumbo frames have been enabled on iSCSI NICs.
Note: The valid display values shown in the output of the get-netadapteradvancedproperty command will vary depending upon the device driver provided by the NIC manufacturer. For example, Broadcom NICs use a jumbo frame value of “9014” while Intel NICs will use a value of “9014 Bytes.”
PS C:\> get-netadapteradvancedproperty –name SAN* -displayname "Jumbo Packet" | ft –property Name, Displayname, Displayvalue, validdisplayvalues -AutoSize
Name Displayname Displayvalue validdisplayvalues
---- ----------- ------------ ------------------
SAN1 Jumbo Packet 9014 Bytes {Disabled, 4088 Bytes, 9014 Bytes} <--- Jumbo Frames Enabled
SAN2 Jumbo Packet 9014 Bytes {Disabled, 4088 Bytes, 9014 Bytes} <--- Jumbo Frames Enabled