Chapter 4: Server Configuration Utility

The Server Configuration utility enables you to change the configuration of your personal XDB Server. For example, you can change the following:

• The XDB Server name
• Whether XDB Server security is enabled or not
• Which protocol is used to access the XDB Server
• Whether other people can use the XDB Server
• The amount of system resources available to XDB Server

Accessing the Server Configuration Utility

On Windows environments, you can run the XDB Server Configuration utility in one of two modes:

• Blue screen – the XDB Server Configuration utility runs as part of the development environment and is available on all Windows environments.

  To start the XDB Server Configuration utility in blue screen mode, click SQL For DB2 > XDB Server on the Options menu.

• Service – the XDB Server Configuration utility runs as a Windows service.

  To start the XDB Server Configuration utility as a service, start your Windows Control Panel, double-click Micro Focus XDB Server, then click Configure.

Server Configuration Parameters

This section covers the following topics:

• System Location Path
• Temporary File Path
• Server Security
• System Usage Monitor
• Sort Space Size
• Lock Table Size
• Maximum Number of Open Queries
• Maximum Number of Open Files
• Governor Cycle Time
• XDB Server Name
• Communications Protocols
• Global Security and Global Security Location Name
• Buffer Pool Size

System Location Path

The system location path specifies where the XDB Server looks for system tables containing information about all locations that are accessible to this XDB Server. These system tables are in addition to the system tables that are maintained in the DSNDB06 database for each location.

Enter a path to a specific drive (volume) and directory. Do not specify a location name.

To set the parameter on Windows NT or 2000:

1. Click the Paths tab.
2. Enter the path in the System Location Path text box.

Temporary File Path

Set the temporary path to identify where the system should write temporary files used by the XDB Server, such as temporary files that are written when a sort operation overflows the allocated Sort Space Size. Enter a path to a specific drive (volume) and directory. This directory must be accessible to the XDB Server.

To set the parameter on Windows NT or 2000:

1. Click the Paths tab.
2. Enter the path in the Temporary File Path text box.

Server Security

The XDB Server is shipped with security turned off. If you enable security at the server, you must also enable security at each client workstation accessing the XDB Server. Otherwise, the XDB Server will reject the client logon.

Enabling security requires each user to log in to the XDB Server using a valid AuthID (user name) and password. To set AuthIDs, groups and passwords, use the Admin menu of the SQLWizard; see the SQLWizard User's Guide for more information. See the Security and Authority chapter, or User Administration in the SQLWizard User's Guide for more information.

If you enable security, the system will also check any privileges configured using the GRANT and REVOKE commands. For information about the GRANT and REVOKE commands, see the SQL Reference.

See the chapter Security and Authority for detailed information about how to plan and construct a security scheme.

To set the parameter on Windows NT or 2000:

1. Click the General tab.
2. Mark the Server Security checkbox.

Server Version

The XDB Server is shipped with version set to DB2V6.

To set the parameter:

1. Press F3 SQL Engine Options.
2. Press F2 Server Version.
3. Press F1 to select DB2V6 or F2 for DB2V7.

System Usage Monitor

The Usage Monitor is a facility for recording location usage. While utilization monitoring is on, the system stores utilization information in the SYSXDB.SYSUSAGE table in the DSNDB06 subdirectory of the system location's directory. If you enable the usage monitor and security, the system will automatically maintain this table, and modify it each time a user logs in or out of a location. You can query the table to audit location usage.

If the SYSXDB.SYSUSAGE table becomes too large, delete entries from the table using the DELETE or TRUNCATE TABLE command. After deleting entries, you must pack the SYSXDB.SYSUSAGE table using the COMPACT command. COMPACT frees space formerly occupied by deleted records. It is good practice to perform this procedure each time you back up the system location when using the System Usage Monitor.

See the SQL Reference for the structure of the SYSXDB.SYSUSAGE table, and for information about the DELETE, TRUNCATE TABLE, and COMPACT commands. As is the case for all XDB Server system tables, the structure of the SYSXDB.SYSUSAGE table is subject to change.

To set the parameter on Windows NT or 2000:

1. Click the General tab.
2. Mark the System Usage Monitor checkbox.

Sort Space Size

Set the sort space size to specify the maximum amount of memory that the XDB Server will attempt to acquire when performing a sort operation. Sort space is acquired on a per-sort basis. The sort space size does not define a common pool shared by all users, but rather the maximum amount of space provided for each individual sort request. If a particular sort process does not require the total amount of memory allocated by the Sort Space Size setting, the excess amount of memory is released back to the operating system.

Increasing the sort space size allows the system to process large sorts more quickly, and store larger amounts of data at a single time, requiring fewer merges of sorted information. However, if you set this value too high, relative to the number of concurrent sorts or users, query processing may slow down significantly due to over-allocated memory.

To set the parameter on Windows NT or 2000:

1. Click the Limits tab.
2. Enter the desired size in the Sort Space Size text box, or drag the slider.

Maximum Number Of Users

Set the maximum number of concurrent users logged in the XDB Server to an integer between 1 and 128. Each user will require an additional 128 bytes of memory.

To set the parameter:

1. Press F4 Configure System Minimums/Maximums.
2. Press F2 Maximum Number of Users.
3. Enter the desired number and press Enter.

Lock Table Size

Set the size of the lock table to an integer between 4 and 1000 (kilobytes). The recommended setting is 60KB. The XDB Server returns an error code when the lock table is full.

To set the parameter on Windows:

1. Click the Limits tab.
2. Enter the desired size in the Lock Table Size text box, or drag the slider.

Maximum Number of Open Queries

You can set the XDB Server to support anywhere from 10 to 9,999 open queries. Each additional query specified here requires an additional, but negligible amount of memory. However, specifying too large a number can impact performance because the array of queries is scanned each time a transaction completes. The more queries that are allowed, the longer the scan will be each time.

To set the parameter on Windows NT or 2000:

1. Click the Limits tab.
2. Enter the desired number in the Maximum Open Queries text box, or drag the slider.

Maximum Number of Open Files

Set the XDB Server to allow between 256 and 32,767 logically open files at any time. Each additional open file adds approximately 100 bytes of memory overhead to the XDB Server.

Once a file has been accessed, the XDB Server keeps the file logically open. A least recently used (LRU) algorithm determines which files to physically close when the limit is reached. The LRU significantly reduces the overhead related to physically opening and closing files during query processing.

If query processing is slow, increase the maximum number of open files.

To set the parameter on Windows:

1. Click the Limits tab.
2. Enter the desired number in the Maximum Open Files text box, or drag the slider.

Governor Cycle Time

If security is enabled, set the governor cycle time to an integer between 1 and 255 to specify the frequency, in seconds, at which the server checks user activity against limits set in the SYSXDB.SYSGOVERNOR table.

The XDB Server terminates sessions of users who have passed their limits. Limit users by the:

• Number of API calls
• Amount of time in the SQL engine
• Amount of time processing calls
• Amount of idle time
• Number of fetches

For example, if Governor Cycle Time is set to 30 seconds, the system checks user activity against governor limits every 30 seconds. A cycle that is too short increases system overhead and decreases performance.

For more information about the XDB Governor and how to assign restrictions to users, see the description in the chapter Security and Authority.

To set the parameter on Windows:

1. Click the General tab.
2. Mark the Governor checkbox (if it is not already enabled).
3. Enter the desired cycle time in the Cycle Time text box, or drag the slider.

XDB Server Name

Use this option to set the name by which this XDB Server is known to client applications. Multiple XDB Servers, each with a unique name, can coexist on the same network. Users must supply the appropriate XDB Server Name, using the Options Utility, to connect their client applications to a particular server.

The name given here must also be specified in other places, depending on the client-to-server communications protocol and operating system:

• For servers using TCP/IP, the xdbnet.ini file contains additional protocol information about each XDB Server on the LAN.

Other networks or operating systems may have other naming conventions and restrictions. Consult your network or operating system documentation for more information.

To set the parameter on Windows:

1. Click the About tab.
2. Enter the name in the XDB Server Name text box.

Communications Protocols

• Local (Windows)

  Turn this option on to enable communication between client and server on the same Windows machine.

• NetBIOS (Windows NT)

  Turn this option on to enable communication between NetBIOS clients and the server.

• TCP/IP (all platforms)

  Turn this option on to enable communication between TCP/IP clients and the server. See the appendix, Troubleshooting for more information about configuring TCP/IP connections.

To set the parameters on Windows:

1. Click the General tab.
2. Mark the checkbox next to the desired communications protocol.

Global Security and Global Security Location Name

Once you enable server security, you may enable Global Security if this XDB Server will access another XDB Server or mainframe location for security information (such as AuthIDs and password validation). If you enable Global Security, you must enter the name of the location that contains the global security information.

• If the global security location is on an XDB Server, you must set up server-to-server connections, including registering the security location of the remote XDB Server in the appropriate system tables of the local XDB Server. See the chapter Server-to-Server Connectivity for more information.

If Global Security is OFF and the XDB Server's regular security feature is ON, AuthID and password validation are performed on the local XDB Server's SYSXDB.SYSACFUSERS, SYSXDB.SYSACFGROUPS and SYSXDB.SYSACFMEMBERS tables in the SYSTEM location.

See the chapter Security and Authority, or User Administration in the SQLWizard User's Guide for information about setting up AuthIDs and groups for users. See the chapter Server-to-Server Connectivity for information about setting up server-to-server connectivity. See the chapter Multiserver Security for information about setting up global security.

When using global security, the following are granted on the XDB Server where the user will be accessing data: server-to-server connections and inbound/outbound mapping database privileges, governor limits, and similar user controls.

To set the parameter on Windows:

1. Click the General tab.
2. Mark the Global Security checkbox.
3. Enter the global security location name in the Location text box.

Buffer Pool Size

You can set a buffer pool size to allocate the total amount of memory, in kilobytes, available for caching table, index, and dictionary files. A buffer pool size can range from 16K to 131,072K. The value of BP(0) sets the buffer pool size for data, and the value of BP(1) sets the buffer pool size for indexes. However, if you set BP(0) to a value of zero, this sets the buffer pool size to zero for both data and indexes.

Micro Focus's buffer management system is designed to enhance performance. Memory is allocated by the cache manager at XDB Server start up and then released at XDB Server shut down.

To set the cache size in blue screen mode:

1. Press F6 Caching Options.
2. Press F1 BP(0) Cache Size or F1 BP(1) Cache Size.
3. Enter the appropriate cache size in KB and press Enter.

To set the cache size from the Windows XDB Server Configuration Utility service:

1. Click the Cache tab.
2. Type a cache size into each of the appropriate fields, or drag the slider to select a value for each.

About Caching

There is one buffer pool cache per XDB Server, and all applications connecting to the XDB Server share this global memory. The overall size of the buffer cache has a large impact on database performance. If the cache is large enough to keep the required data in memory, less disk activity occurs and performance increases. If the cache pool is not large enough, the overall performance of the XDB Server can decrease, with the XDB Server becoming I/O-bound, as physical disk activity is required to service application requests.

The buffer pool cache effectiveness increases with multiple users, when a large amount of repeated access to the same data and index pages occur, and when one primary location is accessed.

The cache manager stores pages (4K each) of database object data. (Therefore, the number of pages is the cache size divided by four.) These database objects consist of table, index, and dictionary pages for all accessed locations. The dictionary pages originate from the dictionary files that reside in every location. As an application requests data from one of these object types, pages containing the data are transferred from the disk into the buffer pool.

Pages are not written to disk until one of the following occurs:

• The XDB Server is shut down.
• A checkpoint occurs.
• Another page needs to be read into a full buffer pool.

Consider the following when determining how much RAM to allocate to cache:

• A large cache usually speeds up online transaction processing (OLTP). However, if the checkpoint frequency is too infrequent, there can be detectable processing delays each time the checkpoint causes data to be written to the location tables. If checkpoint delays are a problem, either lower the cache amount or increase the checkpoint frequency. For more information about the CHECKPOINT command and the Checkpoint Frequency parameter, see the SQL Reference and the chapter Backup and Recovery chapter in this guide.
• Decision support systems usually benefit from a larger cache, but the amount of cache does not necessarily have to be as large as the combined size of the database tables and indexes. For example, in a database where much of the data is historical (and rarely accessed), the amount of cache would only have to be large enough to contain the currently active data -- such as the current month or quarter.
• On systems where sort operations are heavy, you might find that an increase in Sort Space Size gives a better performance gain than increasing or decreasing the cache. Once the appropriate Sort Space Size is defined, you should find it easier to determine the amount of cache needed.

Use the Cache Statistics screen of the Monitor Utility to help determine the best amount of cache for your system. When your XDB Server has reached a steady state (work is well in progress), check the percentage shown for Pages in Use. If Pages in Use is running at or near 100% and the Number of Tosses is high, then most of your allocated cache is being used and you might want to try increasing it. If Pages in Use and Tosses are running low, you have more cache allocated than you need.

See the chapter Performance Tuning for more information about improving production processing. See the topic XDB Server Monitor Utility in the Help Table of Contents for information about the Server Cache Statistics screen.

Copyright © 2007 Micro Focus (IP) Ltd. All rights reserved.