Dell EqualLogic PS6100 series Configuration Manual page 72

Note: A detailed and frequently updated list of recommended switches is maintained in a
separate document:
Validated Components List for EqualLogic PS Series SANs
http://www.delltechcenter.com/page/EqualLogic+Validated+Components
Note: The FS7500 NAS appliance requires the use of 1Gb switches that meet the
requirements in this section.
An EqualLogic SAN consists of one or more hosts connected to one or more PS Series arrays through
a switched Ethernet network.
Note: The minimum network configuration for a PS Series Array consists of a connection
between Ethernet0 on each control module and a network switch. To increase
performance and availability, configure multiple network interfaces on an array and
connect them to multiple switches. EqualLogic does not support Direct Attached
Storage (DAS) configurations.
To support a high performance Dell EqualLogic SAN, switches must meet the following general
requirements:
•
Low latency: Switches with relatively high latency may cause SAN throughput performance to
degrade, and under high load conditions they could increase the risk of dropped connections.
•
Non-blocking backplane design: SAN Switches should be able to provide the same amount of
backplane bandwidth to support full duplex communication on ALL ports simultaneously.
•
Adequate buffer space per switch port: In addition to supporting data transfers between the hosts
and the SAN, Dell EqualLogic arrays also use the SAN to support inter-array communication and
data load balancing. For this reason, the more buffer space per port that a switch can provide the
better. Due to the multitude of buffer implementations used by switch vendors, Dell cannot
provide definitive guidelines as to how much is enough. Port buffers should be designed such that
data is not lost when traffic reaches extreme levels. Due to the clustered storage traffic patterns
used by the EqualLogic SAN architecture, switches that support "cut-through" mode are not
suitable for use in an EqualLogic SAN and may actually result in lower overall SAN performance.
•
Support for IEEE 802.3x flow control (passive and/or active) on ALL ports: Switches and network
interface controllers used in an EqualLogic SAN must be able to passively respond to any "pause"
frames received. If possible, you should use switches that have the ability to transmit "pause"
frames to external devices in the event that the device cannot adequately forward traffic in a timely
fashion.
•
Support for Jumbo Frames: This is not a requirement. But, the use of jumbo frames may yield
desirable results. Most iSCSI SAN implementations should benefit from using jumbo frames. The
actual impact on SAN throughput when using jumbo frames will depend on your workload's I/O
characteristics.
•
Support for Rapid Spanning Tree protocol (IEEE 802.1w), or Cisco "portfast" functionality if the
SAN infrastructure will consist of more than two switches: For SAN infrastructures consisting of
March 2013 Dell EqualLogic Configuration Guide v14.1 7-63