Dot Hill Systems SANnet II 200, Инструкция по установке, эксплуатации и обслуживанию

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7-4 SANnet II 200 SCSI Array Installation, Operation, and Service Manual • June 2005
7.4 Controller Failover
Controller failure symptoms are as follows:
■
The surviving controller sounds an audible alarm.
■
The center LED (status symbol) flashes amber on the failed controller.
■
The surviving controller sends event messages announcing the controller failure of
the other controller.
A “SCSI Bus Reset Issued” alert message is displayed for each of the SCSI channels.
A “Redundant Controller Failure Detected” alert message is also displayed. These
messages are also written to the event log.
If one controller in the redundant controller configuration fails, the surviving controller
temporarily takes over for the failed controller until it is replaced.
A failed controller is managed by the surviving controller which disables and
disconnects from its counterpart while gaining access to all the signal paths. The
surviving controller then manages the ensuing event notifications and takes over all
processes. It is always the primary controller regardless of its original status, and any
replacement controller afterward assumes the role of the secondary controller.
The failover and failback processes are completely transparent to the host.
Controllers are hot-swappable if you are using a redundant configuration, and
replacing a failed unit takes only a few minutes. Since the I/O connections are on the
controllers, you might experience some unavailability between the times when the
failed controller is removed and a new one is installed in its place.
To maintain your redundant controller configuration, replace the failed controller as
soon as possible. For details, refer to the
SANnet II Family FRU Installation Guide .
7.5 Recovering From Fatal Drive Failure
With a redundant RAID array system, your system is protected with the RAID parity
drive and a global spare or spares.
A FATAL FAIL occurs when more drives fail than your RAID redundancy can
accommodate. The redundancy of your RAID array depends on your configuration. In
a RAID 3 or RAID 5 configuration, two or more drives must fail than the number of
spares available for a FATAL FAIL status. In a RAID 1 configuration, you can lose
multiple drives without fatal failure if all the failed drives consist of no more than one
drive from a mirrored pair.
It might be possible to recover the RAID from a FATAL FAIL. However, it might be
impossible to do a full data recovery, depending on the circumstances of the failure. It
is important to check your recovered data using the data application or host-based tools
following a FATAL FAIL recovery.