Method used if multiple hosts share a LUN

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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.

Other related questions:
Does a V3 series unified storage system support the mapping of one LUN to two or more hosts for use?
Yes, one LUN of a V3 series unified storage system can be mapped to two or more hosts for use after you cluster multiple hosts and add the LUN mapping to the host group. After you map the LUN to the host group, the LUN will provide storage space for all hosts in the host group. For details, see Creating a Mapping View.

Whether a T series unified storage system supports the mapping of one LUN to two or more hosts for use
Yes, one LUN of a T series unified storage system can be mapped to two or more hosts for use after you cluster multiple hosts and add the LUN mapping to the host group. After you map the LUN to the host group, the LUN will provide storage space for all hosts in the host group. For details, see Adding a Mapping.

Method used to map a LUN to a cluster host
The storage device needs to map LUNs to host groups.

Method used to query the relationship between storage LUNs and disks on the Linux host
Method used to query the relationship between storage LUNs and disks on the Linux host: This method is applicable only to the scenario where one storage array is mounted on the host. For the scenario where two storage arrays are mounted on the host, contact Huawei technical support. 1. Run lsscsi on the host to query disks mapped on the storage array. You can obtain the host LUN ID corresponding to the disks. 2. Obtain the host LUN ID from the array mapping. Check whether it is the same as that obtained on the host.

Method used to query the relationship between storage LUNs and disks on the Windows host
Method used to query the relationship between storage LUNs and disks on the Windows host: This method is applicable only to the scenario where one storage array is mounted on the host. For the scenario where two storage arrays are mounted on the host, contact Huawei technical support. 1. Right-click My Computer and choose Management from the shortcut menu. 2. Choose Disk Management from the navigation bar on the left, right-click a disk, and choose Property. 3. On the property page, you can obtain the host LUN ID and corresponding driver letters. 4. Obtain the host LUN ID from the array mapping. Check whether it is the same as that obtained on the host.

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