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What this article shares with you is about the principle and use of HDR in the high availability of informix. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Introduction to 1.HDR

HDR (High availability Data Replication) is the oldest high availability solution in Informix, which first appeared in version 6.

HDR dual-computer mutual backup has become the basic platform of 724 system. When any host fails, it can be switched to the standby within 30 seconds, and the business of the enterprise will not be affected.

two。 What is HDR?

HDR is a way to copy data from the primary server to the standby server

* instance-level replication (all databases with logging enabled)

* replication technology based on logical logs, which requires a large number of logical logs to be transferred

Log mode needs to be enabled for the database

* continuously copy data to the standby node over the network

* HDR ensures that the slave server is always synchronized with the master server.

* if the primary server fails, the standby server can take over until the primary server resumes operation.

Characteristics of 3.HDR

-there is only one HDR slave node, which can be read and written.

-High bandwidth and close distance between active and standby nodes

-each node has its own storage device

-can only withstand server software and hardware failures

-unable to withstand natural disasters

4. Configure HDR

prerequisite

-the Informix version of the master / slave server is identical.

-the OS version and hardware of the master and slave servers are basically the same (can be slightly different)

-the amount of disk space allocated to dbspace must be the same on the master and slave servers.

-on the master / slave server, the path and offset of chunk must be the same.

-establish mutual trust between active and standby servers

/ etc/hosts.equiv or / home/informix/.rhosts

-the following ONCONFIG parameters of the master and slave servers must be the same

ROOT DBSPACE parameter

Logical log, physical log parameters

Backup related parameters (ontape, onbar)

DRAUTO 、 DRINTERVAL 、 DRTIMEOUT

-configure SQLHOSTS

? Configure the service name that points to the other party

5. Start HDR for the first time

Step master server (hdr_pri) standby server (hdr_sec)

1 onmode-ky

2 onmode-d primary hdr_sec

Level 30 backup: ontape-s-L 0

4 copy the backup files to the standby server

5 Database recovery: ontape-p

6 onmode-d secondary hdr_pri

7 onstat-l (executed when logical logs on the primary server have been backed up to external media)

Step 3-5 the backup and restore process can be simplified with the following command (version 10 or above)

Execute on the primary server:

Ontape-s-L 0-t STDIO-F | rsh sec_server ".. / hdr_env & & ontape-p-t STDIO"

(hdr_env is the file that sets the environment variables for the standby server)

6.HDR summary

HDR is an enterprise-level solution for dual-computer hot backup.

Logical log-based replication technology ensures that the standby server is always synchronized with the primary server.

When the primary database server fails, the HDR standby server can switch to the primary server and take over

Business to meet 24-hour x 7-day uninterrupted business requirements

HDR supports only one HDR secondary server.

HDR requires high bandwidth, and the deployment distance of active and standby servers is close.

The above is the principle and use of HDR in the high availability of informix. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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