Sas Drive Channel Miswires; Management Connections - IBM System Storage DS3500 Introduction And Implementation Manual

Draft Document for Review March 28, 2011 12:24 pm
Attention: Make sure that you wait at least 30 seconds for the DS Storage Manager
software to recognize each newly added drive before you install another drive.

4.6.7 SAS Drive Channel Miswires

If the SAS cabling on the drive side is incorrect, it will be detected by the DS3500 controller
firmware. The Storage Manager application will alert you about the condition by logging a
critical Major Event Log event. In addition, the Storage Manager Recovery Guru will point to
the miswire condition and advise you of the steps to correct the problem. See 14.13,
"Recovery Guru - Recover from Failure" on page 419 for more information about failure
recovery.
Keep in mind that a miswire condition will only be reported if the wrong SAS connections will
result in a non-working configuration. It is also possible to attach the EXP3500 enclosures in
a technically correct manner which might not be optimal. Such configurations will not produce
a miswire event. Therefore, you should carefully follow the recommendations here for best
results.
Here are a few examples of miswired configurations:
EXP3500 enclosures are connected to SAS host ports instead of to SAS drive ports on
the DS3500 controller.
The SAS IN port is connected to the SAS IN port on another EXP3500.
The SAS OUT port is connected to the SAS OUT port on another EXP3500.
SAS ports are interconnected within a single EXP3500.
An example of a non-optimal, but technically correct configuration would be to connect both
left and right side ESMs in top-to-bottom order. While this configuration does work and does
not result in a miswire condition, it does not provide redundancy. For example, if an entire
EXP3500 fails, the EXP3500 enclosures beneath it will all lose access to the DS3500
subsystem.

4.7 Management connections

There are two connection methods that you can use to manage the DS3500 storage
subsystem. These two methods are called host-agent (in-band) management or direct
(out-of-band) management.
Note: If you have a dual controller DS3500 subsystem, you must ensure that the
management station has a management connection to both controllers. If only one
controller is accessible by the management station, then Storage Manager will not be able
to correctly manage the enclosure.
The installation and configuration of in-band and out-of-band management connections is
described in detail in the Chapter 5, "Installing IBM System Storage DS Storage Manager" on
page 133.
Chapter 4. IBM System Storage DS3500 and EXP3500 Cabling
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