Method used if multiple hosts share a LUN

You can refer to the following case when multiple hosts share a LUN:
To improve the reliability and availability of the system, sometimes multiple hosts must share one LUN. When one LUN is shared by multiple hosts, if a file is used by multiple hosts at the same time, the file may be damaged. To avoid such damages, you must include multiple hosts into a cluster system and manage the hosts.
The cluster system provides highly reliable services for customers, having the following features:
A cluster is a group of independent servers that function and are managed as a single system.
A cluster contains at least two servers with shared data space. Application data of servers is stored in the shared space while their operating systems and program files are saved in their local storage space.
Each cluster node is a server and communicates with each other. If a node server is faulty, anther node server will take over its service. Customers are connected to new application servers without feeling service interruption.
Servers within a cluster perform backups for each other, which achieves high availability. The following is the most common mutual backup modes:
Hot backup. In this mode, servers work in active/standby mode. When applications are running on the active server, the standby server is in the idle state and monitors the running status of the active server in real time. Upon the failure of the active system, the standby server immediately takes over services.
Mutual backup. In this mode, both of the servers are running properly without a division of active and standby servers. The two servers run different applications and monitor each other in real time. If one of the two servers is faulty, the other server immediately takes over its applications without service interruption.
Duplex. In this mode, two or more servers are running properly and run same applications. The high performance of the cluster is ensured with load balancing and mutual backup.
After a cluster is created on the application server, perform the following operations in the storage system:
1. Log in to the ISM and create a host group. For details, refer to section "Creating a Host Group" of the Configuration Guide in the provided documentation CD-ROM.
2. Create hosts in the host group interface. The number and operating system type of hosts must be the same as those of actual hosts. For details, refer to section "Creating a Host" of the Configuration Guide.
3. Map a LUN to the host group so that the LUN can be shared by hosts in the host group. For details, refer to section "Adding a Mapping" of the Configuration Guide.
4. Set up connections between the host and the storage system. For details, refer to section "Connect the Application Server to the Storage Device" of the Configuration Guide.
5. Configure an initiator and connect hosts created on the storage system to the actual physical hosts. For details, refer to section "Configuring an Initiator" of the Configuration Guide.
6. Scan for the host and mount the mapped LUN to the host. For details, refer to section "Making Storage Space Available on an Application Server" of the configuration Guide.
Through the above operations, multiple hosts can share one LUN.

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