The disk signature is used internally by MSCS as a resource parameter. For each shared disk its signature will be recorded in the registry key value.
• HKEY_LOCAL_MACHINE\Cluster\Resources\ <resourceID>\ Parameters\Signature
-Where <ResourceID> is a random based number that uniquely identifies a resource
The Cluster disk driver also records signatures of disks that have been locked (defined as cluster resource) in the value
• HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Services\ Clusdisk\Parameters\Signature\<Sig>\<n>
-where <Sig> is the disk signature of the device listed as <n> in Disk Admin
The definition of disk resources in MSCS is based on disk signatures. The disk signature is used internally as a resource parameter. Because the disk signature values are never shown to the user during normal operation, the Parameter tab of disk resources shows the drive letter and volume label instead of the signature.
The reason that this is extremely important in MSCS is because inconsistencies can cause problems in bringing resources online or "locking" drive letters so they do not appear in Disk Admin after replacing a drive.
Bringing a Disk Resource Online
The Win32 subsystem reads the HKEY_LOCAL_MACHINE\System\Disk\Information value (and the \device\CdRomXX value if one is attached) when using drive letters to represent partitions on the disk with signature <Sig>.
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