InfoScale™ 9.0 Disaster Recovery Implementation Guide - Linux
- Section I. Introducing Storage Foundation and High Availability Solutions for disaster recovery
- About supported disaster recovery scenarios
- About campus cluster configuration
- About replicated data clusters
- About global clusters
- VCS global clusters: The building blocks
- About global cluster management
- About serialization - The Authority attribute
- Planning for disaster recovery
- About supported disaster recovery scenarios
- Section II. Implementing campus clusters
- Setting up campus clusters for VCS and SFHA
- About setting up a campus cluster configuration
- About running a fire drill in a campus cluster
- About setting up a campus cluster configuration
- Setting up campus clusters for SFCFSHA, SFRAC
- Setting up campus clusters for VCS and SFHA
- Section III. Implementing replicated data clusters
- Configuring a replicated data cluster using VVR
- Configuring a replicated data cluster using third-party replication
- Section IV. Implementing global clusters
- Configuring global clusters for VCS and SFHA
- Setting up VVR replication
- Creating a Replicated Data Set
- Creating a Primary RVG of an RDS
- Adding a Secondary to an RDS
- Changing the replication settings for a Secondary
- Synchronizing the Secondary and starting replication
- Starting replication when the data volumes are zero initialized
- Configuring clusters for global cluster setup
- Configuring service groups for global cluster setup
- Configuring a global cluster with Storage Foundation Cluster File System High Availability, Storage Foundation for Oracle RAC, or Storage Foundation for Sybase CE
- Configuring the secondary site
- Configuring global clusters with VVR and Storage Foundation Cluster File System High Availability, Storage Foundation for Oracle RAC, or Storage Foundation for Sybase CE
- Setting up replication on the primary site using VVR
- Setting up replication on the secondary site using VVR
- Configuring Cluster Server to replicate the database volume using VVR
- Configuring global clusters for VCS and SFHA
- Section V. Reference
- Appendix A. Sample configuration files
- Sample Storage Foundation for Oracle RAC configuration files
- About sample main.cf files for Storage Foundation (SF) for Oracle RAC
- About sample main.cf files for Storage Foundation (SF) for Sybase ASE CE
- Appendix A. Sample configuration files
Using the automatic synchronization feature
The Automatic Synchronization feature enables you to transfer the data on the Primary to the Secondary over the network. You can synchronize the Secondary using automatic synchronization either when the application is active or inactive.
The Automatic Synchronization procedure transfers data in the Primary data volumes to the Secondary by reading the Primary data volumes from start to finish and sending the data to the Secondary.
Note:
Automatic Synchronization does not maintain the order of writes; therefore, the Secondary is inconsistent until the process is complete.
The Secondary becomes consistent after the automatic synchronization completes. To use Automatic Synchronization successfully, the network must be sized appropriately. Note that the synchronization will complete only if the Primary receives writes at a lesser rate than they can be sent to the Secondary. If the Primary receives writes at a faster rate than they can be sent to the Secondary, the synchronization might never complete, especially if the writes are dispersed widely in the volume.
This feature enables you to synchronize multiple Secondary hosts at the same time. When performing automatic synchronization to multiple Secondary hosts, synchronization proceeds at the rate of the slowest network.
VVR pauses synchronization if the Secondary fails or the network disconnects. If the Primary fails while synchronization is in progress, the synchronization continues from the point at which it had stopped when the Primary recovers.
Prerequisite for using Automatic Synchronization
Each data volume in the Primary RVG must have a DCM associated to it. If data volumes do not have DCMs, an attempt to automatically synchronize a Secondary fails.
The vradmin startrep command when used with the option -a enables you to start replication and automatically synchronize the Secondary data volumes with the Primary data volumes in an RDS; it brings the Secondary data volumes up-to-date with the Primary data volumes. You can use this command to synchronize the Secondary when the data volumes contain data and when the application is active or inactive. Replication to another Secondary can be started only after this automatic synchronization completes.
The vradmin startrep command can be issued from any host in the RDS. To check the status and progress of the automatic synchronization, use the vxrlink status command on the Primary RLINK.
To synchronize the Secondary and start replication using automatic synchronization, issue the following command:
# vradmin -g diskgroup -a startrep local_rvgname sec_hostname
The argument local_rvgname is the name of the RVG on the local host and represents its RDS.
The argument sec_hostname is the name of the Secondary host displayed in the output of the vradmin printrvg command. If the RDS contains only one Secondary, the sec_hostname is optional.
Example - Using the Automatic Synchronization Feature
In this example, the data volumes in the Primary RVG hr_rvg on host seattle contain valid data and the application is active. To start replication and synchronize the Secondary RVG hr_rvg on host london, issue the following command:
# vradmin -g hrdg -a startrep hr_rvg london