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SAS Multipathing

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SubnetMask

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I received my SAS2-826EL2 backplane today to put in my FreeNAS 'head' so that I could put the SAS2-826EL1 into my JBOD enclosure, and started tinkering with it. At first, I found that only two disks showed up in the 'View Multipaths' area. That was because there were only two disks not assigned. So I removed all the volumes and rebooted, and now everything shows up in the Multipath section. The odd thing is no matter what I do, the lower 'da' numbers are 'hidden' (passive) and the higher ones are the ones listed in 'view disks'. I thought maybe swapping which PCIe slot which controller was in would make a difference, but it didn't.

What's got me a little confused is in the SuperMicro documentation for the SAS2-826EL1/2 backplanes, early on, on page 3-1 (figure 3-1), it shows that J0 for both the primary and secondary expanders should be connected to a HBA or a higher backplane, and that J1 should go to a lower backplane in a cascaded system. On the very next page (3-2), it shows a single HBA with dual links to the expander, one going to Expander 1 port A (J0) and the other going to Expander 2 port B (J1). On the following page (3-3), it shows a similar config as on 3-2, with two HBAs - again, one connected to Expander 1 J0 and the other connected to Expander 2 J1.

Does anyone know which is correct, or if it really matters, since the documentation seems to contradict itself?

Is there any way to 'force' FreeNAS to list the lower number in the disk list and/or use that as the primary?
 

SubnetMask

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No one has any thoughts on this? It seems as if the backplane is setting the secondary expander as primary - in FreeNAS, the expander attached to the primary controller, other than the SATA SSDs, are 'standby', and the secondary contoller is 'Active'.
 

Ericloewe

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Why do you particularly care which one is in use?
 

SubnetMask

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I don't really care which expander is in use, but what's 'driving me nuts' is that the lower numbers, 0-11, except for the SATA SSD that's connected only to the primary HBA, are the standby, so the higher numbers all show up in the 'list disks' section, and that the first 10 graphs in the reporting are the standby paths, so they don't see any usage. Now, replacing all of the multipathed disks (/dev/da0 & /dev/da11 for example) in the reporting and disk list with the multipathed 'diskX'.
 
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