iSCSI Settings
This appendix lists recommended and required settings when using iSCSI cards.
Flow Control Settings
This section provides information about flow control and the recommended flow control settings.
Ethernet Flow Control
802.3x flow control is a mechanism for temporarily pausing data transmission when a NIC, an HBA port, or a switch port is transmitting
data faster than its target port can accept the data.
Ethernet flow control allows a switch port to stop network traffic between two nodes by sending a PAUSE frame to another switch port or
edge device. The PAUSE frame temporarily pauses transmission until the port is again able to service requests.
Switch Ports and Flow Control
Recommendations for using Ethernet Flow Control depends on the switch port hardware.
•
Ethernet Flow Control should be set to ON for switch ports connected to Storage Center storage system card ports.
•
Switch port settings for server NICs and other switch ports in the switch network should be set to ON.
Flow Control
Dell recommends the following settings as best practice when enabling flow control:
•
A minimum of receive (RX) flow control should be enabled for all switch interfaces used by servers or storage systems for iSCSI traffic.
•
Symmetric flow control should be enabled for all server interfaces used for iSCSI traffic. Storage Center automatically enables this
feature.
NOTE:
To find best practices for iSCSI SAN switch configuration, go to the
wiki page.
Jumbo Frames and Flow Control
Some switches have limited buffer sizes and can support either jumbo frames or flow control, but cannot support both at the same time. If
you must choose between the two features, Dell recommends choosing flow control.
NOTE:
All the switches listed in the
Dell EMC Compatibility Matrix for SC, PS, and FS Series Arrays
support both jumbo frames
and flow control at the same time.
However, if you use jumbo frames, be aware of the following:
•
To simplify troubleshooting initial deployments, make sure that all servers, switches, and storage are fully operational before enabling
jumbo frames.
•
All devices connected through iSCSI must support 9K jumbo frames or larger.
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iSCSI Settings
