Dell PS4100 Technical Information download pdf (Page 61)

June 2012 Dell EqualLogic Configuration Guide v13.2 55

Figure 24 Mixed speed redundant SAN using straight interconnect between 1Gb and 10Gb switches

4.6.2 Mixed SAN best practices

The following list summarizes the important SAN design considerations for integrating 10Gb

EqualLogic arrays into existing 1Gb EqualLogic SANs.

• When integrating 10Gb switches into your existing 1Gb environment, how you interconnect

the mixed speed switches (split vs. straight uplink) does not have a significant impact on

performance as long as the uplinks are sized appropriately to your workloads.

o If your 1Gb switches are configured as a stack then you should use the split

interconnect pattern shown in Figure 23 by default.

o If your 1Gb switches are not stacked, then you must use the straight interconnect

pattern shown in Figure 24.

• When connecting 1Gb switches and 10Gb switches together you must always be aware of

where Rapid Spanning Tree is going to block links to make sure that 10Gb traffic (i.e.

EqualLogic inter-array data flow) never crosses the 1Gb switch.

• You must configure pools and volumes in a way that minimizes impact to IO performance.

o If you have predominately 1Gb initiators, start upgrading your arrays to 10Gb for

comparable or better performance across almost all situations.

o If you have predominately 10Gb initiators, you should only access data and volumes

residing on 10Gb arrays (from those initiators). You may see high latency and

retransmit rates when 10Gb initiators connect to 1Gb targets.

o When adding 10Gb arrays, place them in separate pools from your 1Gb arrays.

4.7 Blade Server Chassis Integration

Integrating the PowerEdge M1000e Blade Server Solution (or any third party blade chassis

implementation) requires additional SAN design considerations. Each M1000e can support up to three

separate networking “fabrics” that interconnect ports on each blade server to a pair of blade IO

modules within each chassis fabric through an intervening chassis midplane interface. Each fabric is

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Dell PS4100 Technical Information Page 61