IBMi.org – Bart's blog

IBM i and PowerVM features and tools

Triple backplane – discrepancy between Redbook vs offical doc

In a Redbook I found a pretty serious discrepancy about disk drive location, if you run a triple split backplane.The Redbook “IBM REDP-4924-00” chapter 2.9.2 describes a scenario with three SAS controllers. On page 83 you can find following picture

triple_split_disks

According to the Redbook the SAS controllers located on a backplane operates first two disks in horizon order SAS1(D1-D2), SAS2 (D4-D6), and the an additional SAS adapter controls last two disks in vertical order (D3-D6).

But the official technical documentation shows that all SAS adapters controls disks in vertical order here

triple_split_disks_IBM_doc

When I was about to move configuration from two-way to triple way backplane, I really afraid which document is correct.

In the end, the official document is correct.

This misleading Redbook information might have serious consequence with potentially impacting user data. If a user run a mirror between disks, he doesn’t know if disks are going to be a part of SAS1 or SAS2 configuration.

I’m going to inform the Redbook authors

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One response to “Triple backplane – discrepancy between Redbook vs offical doc

  1. m88 November 25, 2014 at 13:51

    I’ve learn some just right stuff here. Certainly price bookmarking
    for revisiting. I wonder how so much effort you put to make this sort
    of great informative site.

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