Server memory requirements - Firebird

Server Memory (All Platforms)

Estimating server memory involves a number of factors:

  • Firebird server process: The Firebird server process makes efficient use of the server’s resources. The Superserver utilizes around 2MB of memory. On POSIX, the Classic server uses no memory until a client connection is made. On Windows, a small utility service is listening for connection requests.
  • Client connections: Each connection to the Superserver adds approximately 115K, more or less, according to the style and characteristics of client applications and the design of the database schema. Each connection to the Classic server uses about 2MB.
  • Database cache: The default is configurable, in database pages. The Superserver shares a single cache (with a default size of 2,048 pages) among all connections and increases cache automatically when required. The Classic server creates an individual cache (with a default of 75 pages) per connection.

As an estimate, allow 64MB of available RAM for a server and 16MB for a local client. The more clients you add, the more RAM will be used. Databases with large page sizes consume resources in larger chunks than do those with smaller page sizes. Resource usage on the Classic server grows by a fixed amount per client attachment; on Superserver, resources are shared and will grow dynamically as needed. Firebird 1.5 will use extra available RAM for sorting if it is available. Memory usage is discussed in more detail in Chapter Firebird Server.

Installation Drives

Firebird server —and any databases you create or connect to—must reside on a hard drive that is physically connected to the host machine. You cannot locate components of the server, or any database, on a mapped drive, a filesystem share, or a network filesystem.


You cannot run a Firebird server from a CD-ROM. However, you can attach to a read-only database on a CD-ROM drive that is physically attached to the server.1

Disk Space

When estimating the disk space required for an installation, consider the sizes of the following executables. Disk space, over and above these minimum estimates, must also be available for database files, shadows (if used), sort files, logs, and backups.

  • Server: A minimal server installation requires disk space ranging from 9MB to 12MB, depending on platform and architecture.
  • Client library: Allow 350K (embedded: 1.4MB–2MB).
  • Command-line tools: Allow ~900K.
  • DB administration utility: Allow 1MB–6MB, depending on the utility selected.

Minimum Machine Specifications

Minimum specifications depend on how you plan to use the system. You can run a server and develop database schemas on a minimally configured PC—even a “fast” 486 or a Pentium II with 64MB RAM will run Firebird 1.0.x—but such a configuration

SMP and Hyperthreading Support

Firebird Superserver and Classic server can use shared memory multi-processors on Linux. On Windows, SMP support is available only for Classic server.

Hyperthreading is uncertain and seems to depend on several variables, including operating system platform, hardware vendor, and server version. Some users have reported success; others have had problems. If you have a machine with this feature, try your selected server with it enabled initially, and be prepared to disable it at the BIOS level if performance appears slow.

Processor affinity can be configured at the server level in firebird.conf (v.1.5) or ibconfig/isc_config (v.1.0.x). On Windows, for v.1.0.x and for v.1.5 Superserver, the CPU affinity mask should be set to a single CPU on an SMP machine. For instructions, refer to the section “The Firebird Configuration File” in Chapter Configuration and Special Features.

Operating System

Table shows the minimum operating system requirements for running Firebird servers. However, always check the README files in the /doc directory of your kit for late-breaking information about operating system issues.

Firebird Minimum Operating System Requirements

Firebird Minimum Operating System Requirements

Firebird Minimum Operating System Requirements

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