Why cannot the initial synchronization of the LUN-based remote replication synchronize the file storage pool information?

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The creation sequence of an N8500 LUN-based remote replication is to create a remote replication relationship, start initial synchronization, and then create a file storage pool. Therefore, a file storage pool is created after the synchronization process. After initial synchronization, the secondary LUN does not have the file storage pool information, and an alarm, File storage pools for replication fail to be obtained, will be generated for a disaster recovery test. Therefore, if you want to perform a disaster recovery test, start an incremental synchronization to synchronize the file storage pool information of the primary LUN to the secondary LUN.

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Initial synchronization of OceanStor V3 storage systems
Initial synchronization of remote replication for OceanStor V3 storage systems can be performed online.

What Is the Difference Between Synchronous Remote Replication and Asynchronous Remote Replication
Both synchronous remote replication and asynchronous remote replication can be used in disaster recovery solutions implemented by storage systems to back up data remotely. However, they are implemented in different ways and applicable to different service scenarios. Implementation modes are describes as follows: ? Synchronous remote replication: When a host writes data to the primary LUN, a write request is also sent to the secondary LUN. After both LUNs return a response indicating a successful I/O write, the primary storage system sends the host a response indicating a successful I/O write, implementing real-time data synchronization between the primary LUN and the secondary LUN. ? Asynchronous remote replication: When writing data to the primary LUN, the primary storage system records the changed data. After the primary LUN returns a response indicating a successful write, the primary storage system sends the host a response indicating a successful write. Then, data synchronization is triggered by a user manually or by the system based on user-defined trigger conditions to ensure data consistency between the primary LUN and the secondary LUN. Service scenarios are described as follows: ? Synchronous remote replication requires high bandwidth and low data latency. Therefore, synchronous remote replication is typically used in disaster recovery scenarios where the primary and secondary storage systems are adjacent to each other, such as the intra-city data backup and disaster recovery scenario. ? Asynchronous remote replication is not demanding on bandwidth and data latency. Therefore, asynchronous remote replication is applicable to disaster recovery scenarios where the primary and secondary storage systems are far away from each other or the network bandwidth is limited.

Why Does Asynchronous Remote Replication Site Recovery Need Multiple Synchronization Operations?
Multiple synchronization operations help minimize the write delay between the primary LUN and the secondary LUN. In addition, multiple synchronization operations are performed at short intervals. In this case, if you stop services and initiate data synchronization again, incremental data can be quickly synchronized before new write I/Os arrive. This prevents data loss and minimizes the downtime.

How Long Does It Take for Data to Be Replicated to the Remote Storage System After a Pair Synchronization Is Started?
Note that a remote storage system is not equal to the secondary storage system. Data can only be replicated from the primary storage system to the remote storage system. Therefore, when the local storage system is the primary storage system, data of the local storage system can be replicated to the remote storage system after the replication pair is synchronized. However, when the local storage system is the secondary storage system, data cannot be replicated to the remote storage system after the pair synchronization. The data replication time is determined by the following factors: The amount of data to be replicated (initial synchronization) The amount of data changed after the last synchronization (non-initial synchronization) Network bandwidth Performance of storage nodes and disks Number of storage nodes that participate in remote replication Workload of concurrent system tasks Replication transmission rate of a pair

How to use a secondary LUN in a remote replication?
In a remote replication, the secondary LUN and the primary LUN form a pair, and the secondary LUN backs up data on the primary LUN. ? By default, the secondary LUN cannot be accessed (read or written) by a host. If a request is made to access data on the secondary LUN, you can create a virtual snapshot for the secondary LUN, and then map the virtual snapshot to the host for access. ? When a primary LUN encounters a critical error and the services are interrupted, you must perform the master/slave switchover to switch the secondary LUN to the primary LUN, and then map the new primary LUN to the host for access. NOTE: For details on how to perform a master/slave switchover, choose Help > Help Topics on the ISM, and view the related help information.

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