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Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
Enterprise Replication
The HCL® Informix® Enterprise Replication Guide describes the concepts of data replication using Informix Enterprise Replication, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.
Planning and designing for Enterprise Replication
Before you set up your replication system, plan how to include Enterprise Replication into your database server environment, design your database schema by following Enterprise Replication requirements, and then design your replication system between database servers.
Plan for Enterprise Replication
Before you design a replication system, you must understand how Enterprise Replication interacts with the database server and the other requirements of Enterprise Replication. Many aspects of the Informix® database server can affect how you deploy Enterprise Replication.
Transaction processing impact
Many variables affect the impact that replicating data has on your transaction processing.

Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
- System administration
  These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
- Backup and Restore Guide
  The Informix® Backup and Restore Guide describes how to use the Informix ON-Bar and ontape utilities to back up and restore database server data. These utilities enable you to recover your databases after data is lost or becomes corrupted due to hardware or software failure or accident.
- Enterprise Replication
  The HCL® Informix® Enterprise Replication Guide describes the concepts of data replication using Informix Enterprise Replication, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.
  - About Enterprise Replication
    Informix® Enterprise Replication generates and manages multiple copies of data at one or more sites, which allows an enterprise to share corporate data throughout its organization.
  - Planning and designing for Enterprise Replication
    Before you set up your replication system, plan how to include Enterprise Replication into your database server environment, design your database schema by following Enterprise Replication requirements, and then design your replication system between database servers.
    - Plan for Enterprise Replication
      Before you design a replication system, you must understand how Enterprise Replication interacts with the database server and the other requirements of Enterprise Replication. Many aspects of the Informix® database server can affect how you deploy Enterprise Replication.
      - Enterprise Replication Server administrator
        You need special privileges to run most Enterprise Replication commands.
      - Asynchronous propagation conflicts
        Enterprise Replication asynchronously propagates many control operations through the Enterprise Replication network. Avoid operations that might conflict during propagation.
      - Back up and restore of replication servers
        You can back up and restore database servers that participate in Enterprise Replication.
      - Compression of replicated data
        You can compress and uncompress data in replicated tables to reduce the amount of needed disk space.
      - Transaction processing impact
        Many variables affect the impact that replicating data has on your transaction processing.
      - SQL statements and replication
        You can run most SQL statements while replication is active. For some statements, however, you must set alter mode or stop replication.
      - Global language support for replication
        You can replicate data in non-default locales.
      - Replication between multiple server versions
        You can set up Enterprise Replication across servers of different version levels.
    - Schema design for Enterprise Replication
      When you design the database and tables for replication, you must follow the requirements and restrictions for Enterprise Replication.
    - Replication system design
      When you design a replication system, you make three main decisions: how the information flows between servers, how to resolve conflicts between replicated data, and the topology of the network of servers.
  - Setting up and managing Enterprise Replication
    After you design your replication system, you define it and start replication.
  - Push data feature
  - Loopback replication
  - Appendixes

Transaction processing impact

Many variables affect the impact that replicating data has on your transaction processing.

Replication volume

To determine replication volume, you must estimate how many data rows change per day. For example, an application issues a simple INSERT statement that inserts 100 rows. If this table is replicated, Enterprise Replication must propagate and analyze these 100 rows before applying them to the targets.

Distributed transactions

A distributed transaction is a transaction that commits data in a single transaction over two or more database servers.

Outside of the replication environment, Informix® uses a two-phase commit protocol to ensure that the transaction is either committed completely across all servers involved or is not committed on any server. For more information about the two-phase commit protocol, see the Informix® Administrator's Guide.

In a replication environment, when a distributed transaction is committed across the source servers, each part of the transaction that applies to the local server is written to the local logical logs. When Enterprise Replication retrieves the transaction from the logical logs and forms its transaction data, it is unable to identify the separate transaction data as the original single transaction.

This situation might result in Enterprise Replication applying one transaction successfully while aborting another. Another result might be a time lapse between the application of one transaction and another (depending on how much transaction data is in each server's send queue and the state of the server).

Large transactions

While Enterprise Replication is able to handle large transactions, it is optimized for small transactions. For best performance, avoid replicating large transactions.

Large transactions are handled with a grouper paging file in temporary smart large objects. Enterprise Replication can process transactions up to 4 TB in size. For more information, see Setting Up the Grouper Paging File. You can view Enterprise Replication grouper paging statistics with the onstat -g grp pager command (see onstat -g grp: Print grouper statistics).

Instead of using Enterprise Replication to perform a batch job, use BEGIN WORK WITHOUT REPLICATION to run the batch job locally on each database server. For more information, see Blocking Replication.