The Perc 310 has two SAS controller connectors, SAS-A and SAS-B. Each of these supports which has 4 internal mini-SAS, providing a total of eight lanes of PCI Express.

Question is how do these two connectors SAS-A & SAS-B map to physical disk slots in the backplane?

Server will have four raid 1+0 drives and I want to ensure they are correctly laid out so that if one controller channel fails it has the correct mixture of disks on the other channel to keep running.



The Dell PowerEdge T420 Systems Owner's Manual provides no additional information on which disks are attached to each cable. Other documentation describes even less. Simplicity suggests either drives 0-3 and 4-7, or odd and even drives in SAS-A and SAS-B respectively. This looks reasonable from the layout in Figure 29.

I would try by removing half the drives, and seeing what the diagnostics indicate is connected to the machine. Then, try an alternative configuration to confirm your hypothesis.

Do not confuse the SAS channels with the PCIe lanes. The correspondence is a results of balancing throughput and not actual matched traffic.

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Have now found out from elsewhere but note here for the archives: SAS-A = slots 0-7 SAS-B = slots 8-15

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