[Figure] Mirroring Configuration

Mirror Mode

Mirror mode employs both asynchronous and synchronous mirroring schemes. Understanding the advantages and disadvantages between synchronous and asynchronous mirroring is essential to the correct operation of this.

Async mode

With asynchronous mirroring, each write is captured and a copy of this is made. That copy is queued to be transmitted to the target system as soon as the network will allow it. Meanwhile, the original write request is committed to the underlying storage device and control is immediately returned to the application that initiated the write. At any given time, there may be write transactions waiting in the queue to be sent to the target machine.  But it is important to understand that these writes reach the target volume in time order, so the integrity of the data on the target volume is always a valid snapshot of the source volume at some point in time.  Should the source system fail, it is possible that the target system did not receive all of the writes that were queued up, but the data that has made it to the target volume is valid and usable.

Semi-sync mode

With semi-synchronous mirroring, each write is captured and transmitted to the target system. Local write completes in the source as soon as the replication packet has reached the target. Normally, no writes are lost in case of failover , but this may can be lost when both nodes are failed simultaneously. 

Sync mode

With synchronous mirroring, each write is captured and transmitted to the target system to be written on the target volume at the same time that the write is committed to the underlying storage device on the source system.  Once both the local and target writes are complete, the write request is acknowledged as complete and control is returned to the application that initiated the write.  With synchronous mirroring, each write is intercepted and transmitted to the target system to be written on the target volume at the same time that the write is committed to the underlying storage device on the source system.  Once both the local and target writes are complete, the write request is acknowledged as complete and control is returned to the application that initiated the write.

Adding

Add the shared disk DR resource to a group.

1. When add a resource from a group name, select a group → right click → 'Add Resource'. 
2. Select 'SharedDisk DR' from Resource Type lists and click 'Next' button. 

3. Enter the resource name and select mirror volume of shared disk in the cluster.

   
   [Figure] Shared Disk DR Resource Added
   

       

4.  "추가 정보"를  클릭하여 클러스터링되지 않은 원격지 호스트의 구성 정보를 확인합니다.

   
   [Figure] Shared Disk DR Additional Setting

    

5. 공유 디스크 DR 리소스 추가 완료 버튼을 누르면 아래와 같은 경고창이 출력됩니다. 
   선택한 서버가 소스서버가 맞는지 다시 한번 확인합니다.  
   잘못 설정했다면 '취소' 버튼을 누르고 다시 설정합니다. 
    
   [그림] 공유 디스크 DR 리소스 추가 완료 버튼을 클릭 했을 때 출력되는 경고창    
   
   
6. 완료 버튼을 클릭하면 공유 디스크 DR 리소스가 추가 됩니다.
   

Deleting

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1. 리소스 삭제를 클릭하면 MCCS 에 구성된 공유 디스크 DR 리소스를 삭제할지 물어봅니다.
   
   [그림] 리소스 확인 화면    
   
   
2. 확인을 클릭하면 모두 삭제 됩니다.

State

The following table explains the state of shared disk DR resource.

Attribute

Show the specified attribute of mirror disk resource.

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