Disaster Recovery

Advanced Recovery Tasks

 

Restoring Hard Disk Signatures On Windows

 

The MSCS service uses a hard disk signature written into the MBR of

 

every hard disk to identify physical disks. If the shared cluster disks

 

have been replaced, this means that the disk signatures were changed

 

during Phase 1 of disaster recovery. As a consequence, the Cluster

 

Service will not recognize the replaced disks as valid cluster resources,

 

and cluster groups depending on those resources will fail. This applies

 

only to the restore of the active node, since shared cluster resources are

 

operational as long as at least one of the nodes is up and running and

 

claims ownership of the resources. This problem does not apply to EADR

 

and OBDR critical disks because the original disk signatures of all

 

EADR/OBDR critical disks are automatically recovered. In case you have

 

replaced any other disks, you will have to restore their hard disk

 

signatures as well.

 

The most critical shared disk is the cluster quorum resource. If it has

 

been replaced, than the original disk signature must be restored, or the

 

cluster service will not start.

 

During Phase 2, the MSCS Database is restored into the

 

\TEMP\ClusterDatabase directory on the system volume. After the

 

system is rebooted, the cluster service will not be running, because the

 

quorum resource will not be identified due to the changed hard disk

 

signature in Phase 1. This can be resolved by running the clubar utility

 

(located in the <Data_Protector_home>\bin\utilns), which restores

 

the original hard disk signature. After clubar successfully finishes, the

 

cluster service is automatically started.

Example

At the command prompt type clubar r c:\temp\ClusterDatabase

 

force q: to restore a MSCS Database from c:\temp\ClusterDatabase.

 

For more information on clubar usage and syntax, see the clubar.txt

 

file located in the <Data_Protector_home>\bin\utilns.

 

If the Data Protector shared disk on the Cell Manager is different from

 

the quorum disk, it has to be restored as well. To restore the signature of

 

the Data Protector shared disk and any other application disk, you

 

should use the dumpcfg.exe utility included in the Windows 2000

 

Resource Kit. For details on using dumpcfg.exe, run dumpcfg /? or see

 

the Windows 2000 Resource Kit documentation. For more information on

 

the problems with hard disk signatures on Windows 2000, see MSDN

 

article Q280425.

Chapter 10

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