1. Introduction
SAP Sybase Replication Server is database replication software that moves and synchronizes data across the enterprise to meet a host of competing needs, including guaranteed data delivery, real-time business intelligence and zero operational downtime. SAP Sybase Replication Server maintains replicated data in multiple databases and provides clients using databases in the replication system with local data access, thereby reducing load on the network and centralized computer systems. In the latest release, version 15.7.1 SP100, a new feature, is introduced and packaged in SAP Sybase Replication Server, HANA Edition.
1.1 Functions of SAP Sybase Replication Server
The SAP Sybase Replication Server, HANA Edition provides the following main functions:
- Replicates data across networks using publish-and-subscribe model.
- Provides communication between SAP Sybase Replication Servers via user-defined routes.
- Enables management of replication functions and monitoring and maintenance of the replication system by means of Replication Command Language (RCL).
- Log-based, real time change data capture from source databases including Oracle, SAP ASE, IBM DB2 LUW, and Microsoft SQL Server for non-SAP applications.
- ExpressConnect for HANA (ECH) to leverage native HANA connectivity for high performance.
- Heterogeneous direct load materialization (a.k.a. initial load).
- Preserves transactional consistency between source databases and HANA target.
- Flexible deployment over LAN / WAN, with multiple sources to multiple target topology support.
- Data Assurance to ensure distributed data consistency.
1.2 Architecture of SAP Sybase Replication Server, HANA Edition
SAP Sybase Replication Server is an Open Server application that uses the SAP Sybase Open Client/Server (OC/S) for network communication and other platform dependent functions, such as connection management, login protocol, data transmission, T-SQL interface, inter-process communication, etc. SAP Sybase Replication Sever also provides log-based Replication Agents for SAP Sybase ASE, Oracle, IBM DB2/UDB and Microsoft SQL Server for non-intrusive, low impact, real time change data capture.
SAP Sybase Replication Server distributes data to one or many databases and uses a basic publish and subscribe model for replicating data across networks. Users ‘publish’ data in a primary database, and other users ‘subscribe’ to the data for delivery into a replicate HANA database.
Figure 1: SAP Sybase Replication Server, HANA Edition Architecture
SAP Sybase Replication Server depends on data servers to provide the transaction-processing services needed to protect stored data. Connections and routes define the structure of the replication system.
Figure 2: SAP Sybase Replication Server, HANA Edition Landscape
Figure 2 illustrates how data is replicated from heterogeneous source databases to replicate HANA databases over LAN or WAN. The following actions take place:
1. RepAgent accesses the source database log and converts transactions for tables or stored procedures that are marked for replication into commands that are sent to Replication Server. The Replication Server stores the transactions in a stable queue using distributed concurrency control.
2. The primary Replication Server:
a. Determines which Replication Servers manage replicate databases with subscriptions for the data. The primary Replication Server may have a direct route to a subscribing Replication Server or an indirect route, with one or more intermediate Replication Servers in between.
b. Forwards the transaction to the appropriate replicate Replication Server, where it is stored in a stable queue
c. Applies the transaction to any local replicate HANA database for which there is a subscription for the data
3. The replicate Replication Server performs one or both of the following actions:
• Routes the transaction to another Replication Server
• Applies the transaction to replicate HANA databases that it manages
1.3 Factors that influence performance
Some factors that influence performance of SAP Sybase Replication Server include:
- CPU
- Memory
- Network
- Disk
- Primary and secondary database server performance
2. Sizing Fundamentals and Terminology
This section explains the most important sizing terms, as these terms are used extensively in this document.
Log transfer rate
Log transfer rate is the rate at which SAP Sybase Replication Server can replicate a given volume of primary database transaction log.
Latency
Replication latency is the amount of time it takes for a transaction that occurs in the primary database to be applied to the replicate database. The time includes Replication Agent processing, SAP Sybase Replication Server processing, and network usage.
Sizing
Sizing means determining the hardware requirements of an SAP software, such as the network bandwidth, physical memory, CPU processing power, and I/O capacity. The size of the hardware and database is influenced by both business aspects and technological aspects. This means that the number of users using the various application components and the data load they put on the server must be taken into account.
Benchmarking
Released for technology partners, benchmarks provide basic sizing recommendations to customers by placing a substantial load upon a system during the testing of new hardware, system software components, and relational database management systems (RDBMS). All performance data relevant to the system, user, and business applications are monitored during a benchmark run and can be used to compare platforms.
Configuration and System Landscaping
Hardware resource and optimal system configuration greatly depend on the requirements of the customer-specific project. This includes the implementation of distribution, security, and high availability solutions by different approaches using various third-party tools. In the case of high availability through redundant resources, for example, the final resource requirements must be adjusted accordingly.
There are some "best practices" which may be valid for a specific combination of operating system and database.
3. Sizing for SAP Sybase Replication Server, HANA Edition
The sizing guidelines provided are based on benchmarking from source Oracle database to target HANA database replication for both materialization and real time replication for a non-SAP application environment. Other source databases to HANA replication sizing guidelines will be provided in future updates.
Workload was configured to limit the CPU utilization to 65% for the SAP Sybase Replication Server system.
Sizing is based on a well-tuned SAP Sybase Replication Server configuration consisting of:
- A single Oracle source and single HANA target
- Source and target connections to and from SAP Sybase Replication Server
- SAP Sybase Replication Agent for Oracle is deployed on the same host as source Oracle database
- A table with 40 columns
- A single table level replication definition for source database
- A single table level subscription for replication to target database
Figure 3: SD Benchmark Replication Server configuration
3.1 Assumptions
- The source Oracle database server is configured to use SAP Sybase Replication Server
- Minimal tuning of SAP Sybase Replication Agent for Oracle and Replication Server parameters were performed and documented in the appendix.
3.2 Sizing guideline
SAP offers a simplified approach with three different Replication Server scenarios.
Custom configuration and tuning of the replication environment may be required under certain conditions (e.g. increased replication throughput for configuration “XL”). Please contact SAP for such requirements and assistance.
Results below should be used as a guideline for expected performance on comparable hardware for similar workload, schema and transaction profiles. These results will apply to most replication environments, but does not guarantee similar results in all cases.
Configuration | Use Case | Latency (sec) | Machine Requirement |
S | A small scenario with: An overall expected throughput of less than 5,000,000 records/hour (25,000,000 records/hour for initial materialization) | < 5 sec | Data transfer job: 1 (max_mat_load_thread =4) Hardware: 4 cores Memory: 6 GB |
M | A midrange scenario with: An overall expected throughput of less than 8,000,000 records/hour (50,000,000 records/hour for initial materialization) | < 5 sec | Data transfer jobs: 2 config(max_mat_load_thread =4) Hardware: 8 cores Memory: 12 GB |
L | An upper mid-range scenario with: An overall expected throughput of up to 11,000,000 records/hour (100,000,000 records/hour for initial materialization) | < 5 sec | Data transfer jobs: 4 (max_mat_load_thread =4) Hardware: 16 cores Memory: 24 GB |
XL | Please contact SAP | ||
Table 1: Sizing guide recommendation
4. Miscellaneous
Measurements are done with SAP Sybase Replication Server 15.7.1 SP100.
Performance, Benchmarks, and Sizing References:
User Guides http://infocenter.sybase.com
See the Performance Tuning section of the Sybase Replication Server Administration Guide
- SAP Managed Tags:
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