An Overview of Reality Administration

This topic briefly defines the relationship between Reality and its UNIX/Linux or Windows host and the implications for Reality administration. It then outlines the Reality administration tasks performed from Reality and the host system environment.

Introduction

Reality can run under UNIX (including Linux) or Windows, creating a Reality Applications Support Environment with one or more databases.

Note: Under normal circumstances, all the databases you create on a host will be associated with the same copy of Reality. Although each database is completely separate, problems that affect the underlying Reality system can affect all databases. If you want to prevent this, you can use the Database Isolation feature that allows you to have multiple copies of Reality, running independently of each other.

Administrative utilities are supported which can be run from both TCL and the host system environment; that is, the UNIX shell or Windows Command Prompt. Reality also provides TCL and host commands that allow Reality and the host system environment to be integrated. Integration between Reality and UNIX and Reality and Windows are discussed in Reality/Host Integration.

Types of Database

Two types of Reality database can be created:

Partition database. This can be constructed in three ways:
- Using standard host files on different file systems – this is available on both UNIX and Windows and gives the best performance on systems other than Solaris. If the file systems are on different spindles, the files can be striped by Reality to improve performance.
- Using disk partitions directly – this is available on UNIX only and is optimised for use on Sun Solaris systems. The partitions are striped by Reality to improve performance.
- Using standard host files with all the files on the same file system – this is available on both UNIX and Windows and is simple to configure. Reality striping is not possible, so the response can be slower when compared to the other types of partition database (depending on the efficiency of any striping performed by the operating system). Its use is not recommended where high performance is required and/or a large number of users must be supported.
Partition databases are initially created with fixed size but can be expanded later. You cannot contract a partition database (though you can save the data and restore it onto a new database).

Filestore database (UNIX only). This is simple to configure, but has limitations when compared to the other types of database. It is best suited to small databases such as those used for test purposes.

A filestore database is constructed using the host file system. Each Reality dictionary and data file equates to a normal host file and each account is equivalent to a host directory. Because of this, a filestore database expands and contracts as you add and delete data.

Different types of database can co-exist on the same system. You choose the type when you create the database.

Database Type Comparison
	Partition database			Filestore database
	Using host files on different file systems	Using disk partitions	Using host files on one file system
Availability	UNIX, Windows	UNIX only (optimised for Solaris)	UNIX, Windows	UNIX only
Scope	Multiple file systems	Dedicated multiple partitions	Single file system	Single file system
Maximum size	2³¹ frames (2 Terabytes if using the default 1Kbyte frame size)	2³¹ frames	2³¹ frames	Depends on the size of the file system
Maximum file size	Up to the size of the database	Up to the size of the database	Up to the size of the database	2 Gbytes
Maximum number of open files	No limit	No limit	No limit	Fixed limit (operating system dependent)
Simultaneous access to different parts of a file	Allowed	Allowed	Allowed	May be restricted by operating system
Reality disk striping to improve performance	Yes (if file systems are on different spindles)	Yes	No (but can be striped by operating system)	No (but can be striped by operating system)
On-line file resizing	Yes	Yes	Yes	No
Automatic file resizing	Yes	Yes	Yes	No
Automatic database resizing	No	No	No	Yes
Physical backup	Yes	Yes	Yes	No
Shadow database	Not recommended	Yes	Yes	Yes
Requires realfstab entry	Yes	Yes	No	No
Supports 2/4/8Kbyte frame sizes	Yes	Yes	Yes	No

Database Size

When deciding what size to make your database, you need to consider the following:

Only 80% of the space in the data files/partitions is available for data.
Reality system files, etc. will occupy 11000 frames of the data files/partitions.
You should allow at least 20% work space for updates (even if you do not expect your database to grow substantially). This requirement can be reduced if the database is not expected to need updating.
Each database will require about 10% additional disk space for temporary files created during normal operation. This will normally be in the file system containing the database's top or root directory, but can be moved to a different location by setting the TempDir database configuration parameter.

Administration in the Host System Environment

The following tasks are performed from the system environment:

Note: If you are using Database Isolation, these commands operate on the currently selected instance of Reality.

Note: The next three procedures can also be carried out from Reality. See Administration in Reality.

Locking and unlocking a database.
Monitoring file size.
Dynamic resizing of Reality files.
Customising user entry (UNIX only).
Database configuration.
Enabling and administering password integration (UNIX only).
Setting up daemon log rotation.
Setting up system command prompt security.
Setting up Reality ports - using PLId to port mapping.
Setting up private printers (UNIX only).
Allocating TIPH ports (UNIX only).
Backup and recovery of databases. See also Save and Restore.
Configuring network connections.
Dealing with system problems.
Configuring System Alerts.
Configuration and administration of isolated instances of Reality (Database Isolation).

Administration in Reality

The following tasks are performed from Reality:

Configuring database security.
Creating and managing accounts.
Customising database logons. See Administration from Reality.
Locking and unlocking a database. See Administration from Reality.
Monitoring database status. See Administration from Reality.
Monitoring file size. See Administration from Reality.
Dynamic resizing of Reality files. See Administration from Reality.
Some parts of network configuration. See Networking.
Dealing with system problems.