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Deploying Microsoft SQL Server 2008 based Decision Support Systems using Dell EqualLogic 10GbE iSCSI Storage 11
Jumbo frames are Ethernet frames that have a MTU larger than 1518 bytes. Jumbo frames can
increase SAN throughput by allowing more data to be transferred in each Ethernet frame. This will
reduce the time it takes to transfer large amounts of data across the SAN.
In our testing we enabled flow control (TX and RX) and used jumbo frames with a MTU setting of 9216
bytes on the switch ports. The jumbo frame size on the switch ports must match or exceed the
settings at the end device ports (the server and storage NICs). Generally end-devices conform to a
jumbo frame setting of at least 9000 bytes.
It is a best practice to enable flow control (both TX and RX) and jumbo frames on all ports, including
LAG ports. In both test configurations we obtained maximum end-to-end throughput when we
enabled flow control and jumbo frames on all iSCSI SAN switch ports (including LAG virtual ports).
4.2.3 PayAttentiontoSpanningTree
In our test configurations we disabled Spanning Tree Protocol (STP) on all switch ports connecting to
end devices (the server and storage controller NICs). We also enabled the “portfast” setting on those
switch ports.
Since NIC and storage controller ports are end points they cannot create loops. Thus you should
enable the ‘portfast’ setting on those switch ports instead. With port fast enabled you eliminate the STP
forwarding state delay time that occurs when a port becomes active. This will accelerate initialization
of new iSCSI sessions if ports on an existing iSCSI connection path change status. This becomes very
important in larger SAN fabric configurations with multiple hops.
4.2.4 SelectAppropriatePhysicalInterconnects
The Dell PowerConnect 8024F switches support SFP+ ports for 10Gb Ethernet connectivity. 10GBASE
SFP+ support is typically provided with 10GbE switches. Either SFP+ transceivers along with optical
cables or SFP+ copper cables can be used for inter-connecting switches and for connecting end
devices to the switches. SFP+ transceivers along with optical cables will support longer distances than
SFP+ copper cables. Connection distance and cost will determine the type of the physical connection
you use. The various physical connection options for SFP+ 10Gb Ethernet are provided in Appendix C ,
SFP+ Connectivity Options, on page 24.
4.3 Server Configuration
You should consider the following best practices when configuring servers for a DSS solution.
4.3.1 HardwareConfigurationtoMeetPerformanceandCapacityRequirementsisCritical.
The Dell PowerEdge M710 database server used in this test was configured with two Intel Xeon X5570
quad-core processors and 32 GB of RAM. Our testing shows that this server configuration can
adequately execute the DSS queries to drive the heavy I/O load on the storage arrays as required by
our testing.