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OceanStor 18500, 18800, and 18800F Storage System V100R001C30 Remote Replication Feature Guide 09

This document describes the remote replication feature, in terms of the implementation principle, application scenario, configuration process, and reference information.
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Requirement Analysis

Requirement Analysis

This section analyzes the requirements of a carrier that implements central backup and disaster recovery using the remote replication feature and comes to a conclusion.

Requirement Source

The carrier has a service site at place A (the service site is called site A later in this document). At site A, there is an application server of which the most important application is a user data management application. Data generated by the application server is stored in an OceanStor storage system. The data and bandwidth status of site A is as follows:
  • The daily data change amount is between 100 MB to 200 MB.
  • The total data amount does not exceed 500 GB.
  • The current network bandwidth between the application server and the storage system is 2 Mbit/s.
Since the network is complete and the application is running properly, the carrier prefers to keep the existing network. Figure 2-1 shows a diagram of the existing network.
Figure 2-1  Diagram of the existing network

Table 2-1 and Table 2-2 describe the LUN mapping and IP address allocation on existing devices at site A.
Table 2-1  LUN mapping at site A

LUN Name

LUN Size

Host Mapping


500 GB

Mapped to application server 1

Table 2-2  IP address allocation at site A


IP Address

Subnet Mask


Management network port

Place A suffers natural disasters from time to time. The carrier wants to protect service data at site A against natural disasters and to quickly recover the service data when a disaster happens. The specific requirements are as follows:

  • Data backup and disaster recovery

    Data at site A is automatically backed up to a backup site without interrupting services to minimize data loss upon a disaster. The backup data can be used to quickly recover services at site A after the disaster.

  • Quick service recovery

    Once a disaster happens, site B takes over services with an RTO no longer than 15 minutes.

  • Central data management

    After a new service site (site C) or even more service sites are set up, data from all service sites are backed up to the backup site for central management and reduced deployment and maintenance costs.

  • Data analysis and mining

    Service data can be exported for analysis and mining to support policy-making.

Requirement Analysis and Conclusions

The previous requirements indicate that the carrier needs a disaster recovery solution. Table 2-3 lists the considerations for implementing a remote disaster recovery solution.
Table 2-3  Considerations for implementing a remote disaster recovery solution



Data transfer amount

Inter-city data transfer is subject to the bandwidth. The amount of lost data decreases as the amount of data transferred within a specified period of time increases.

Host performance

Data backup affects services on the host. Services on the host can run properly if the impact of backup on the services is slight.

Data availability

Availability of data at the disaster recovery site is significant for data recovery. Therefore, data at the disaster recovery site must be available any time.

Service continuity

The disaster recovery site must be able to quickly take over services at the service site through a service switchover to protect service continuity.


Other factors need to be taken into consideration include cost as well as central data management and analysis.

The detailed analysis is as follows:
  • Data transfer amount

    At site A, the daily data change amount is between 100 MB to 200 MB, while the available bandwidth is only 2 Mbit/s, which is not adequate for the data change amount. Therefore, the data replication period must be shortened to reduce the amount transferred each time.

  • Host performance
    The carrier requires minimized impact of backup on host performance to ensure host services run correctly. There probably will be multiple service sites that are in different places and comparatively far from the backup site. Therefore, asynchronous remote replication is suitable for this case. Table 2-4 describes advantages of asynchronous remote replication.
    Table 2-4  Advantages of an asynchronous remote replication solution



    Incremental data replication

    Incremental data replication is implemented between the primary and secondary storage systems. Specifically, After the initial synchronization (full replication), only data changes is replicated from the service site to the backup site during each synchronization process. Since the amount of data replicated each time is small, synchronization completes fast.

    No host performance deterioration

    Data replication is between storage systems, occupying no host resources, so it does not affect current services. The quality of service (QoS) does not decrease.

    Quick service takeover

    When a disaster happens, breaking remote replication pairs between the service site and the backup site, the backup site quickly takes over services of the service site.

  • Data availability

    The carrier needs to analyze the backup data and requires that data at site A be quickly recovered after a disaster. Therefore, data at the backup site must be available anytime.

  • Service continuity

    The backup site must be able to quickly take over services when a disaster causes a failure of site A to minimize the loss.

  • Others

    Besides backup and disaster recovery, the carrier hopes backup data be managed centrally and latest data at service sites be available anytime so that services can be analyzed conveniently. Therefore, data at service sites needs to be centrally backed up to one site. In this way, copies of all data can be quickly obtained when necessary.

Based on the former analysis, details of the solution are as follows:

  • To choose the central backup and disaster solution and build a central backup site at place B (equipment at the backup site includes an OceanStor storage system, an application server, a maintenance terminal, and an iSCSI switch)
  • To use asynchronous remote replication for backup and disaster recovery
  • To set up an iSCSI connection between site A and B
Updated: 2019-01-28

Document ID: EDOC1000077758

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