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Diagnosis Guide

Error symptoms, responses, and recoveries

The recovery scenarios describe what a system administrator or operator might see when the IBM Recoverable Virtual Shared Disk component goes into action to recover from system problems.

Recognizing recovery

You know that the rvsd subsystem is performing recovery processing when you see IBM Virtual Shared Disks that are in the active or suspended state, and you did not put them there. Use the IBM Virtual Shared Disk Perspective to display the states of your IBM Virtual Shared Disk nodes. See the chapter on Managing and Monitoring Virtual Shared Disks, section on Monitoring Virtual Shared Disks, in: PSSP: Managing Shared Disks.

If you recognize that recovery is not taking place normally, check if the rvsd subsystem is active on all nodes. Use the IBM Virtual Shared Disk Perspective, or the ha.vsd query and hc.vsd query commands to see if the respective subsystems are active. If active=0 or state=idle for an extended period of time, recovery is not taking place normally. The ha.vsd query command returns output in the following format:

Subsystem         Group            PID     Status
rvsd              rvsd             18320   active
rvsd(vsd): quorum= 7, active=0, state=idle, isolation=member,
           NoNodes=5, lastProtocol=nodes_failing,
           adapter_recovery=on, adapter_status=up,
           RefreshProtocol has never been issued from this node,
           Running function level 

The hc.vsd query command output looks like this:

Subsystem         Group            PID     Status
hc.hc              rvsd             20440   active
 hc(hc): active=0, state=waiting for client to connect

Planning for recovery

You should have disabled or removed all user-provided scripts that issue change-of-state commands to IBM Virtual Shared Disks.

Monitor the activity of the rvsd subsystem using the IBM Virtual Shared Disk Perspective, to become aware of potential problems as soon as they arise. You can begin a monitoring session, leave it in a window on your workstation and go about doing other work while the monitoring activity continues.

Each of the recovery scenarios is organized as follows:

  1. Symptoms
  2. Detection
  3. Affected components
  4. Recovery steps
  5. Restart

Virtual Shared Disk node failure

Switch failure scenarios

The sequence of events triggered by a switch failure depends on whether adapter recovery is enabled.

When adapter recovery is enabled

When adapter recovery is disabled

Topology Services or recovery service daemon failure

Disk EIO errors

If you mirror data from each IBM Virtual Shared Disk to a IBM Virtual Shared Disk on another adapter, you should not experience this type of error.

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