Server Memory Calculations

The c-treeACE Server startup memory requirements can be reasonably approximated with the following equation:

Base line Memory =

    Server EXE size + 1 MB +

    Communications Library size (if applicable) +

    Data cache (DAT_MEMORY) +

    Index buffer (IDX_MEMORY) +

    (900 bytes * Number of files (FILES)) +

    (325 bytes * Maximum number of connections (CONNECTIONS)) +

    (4 bytes * Maximum number of connections (CONNECTIONS)

             * Maximum number of connections (CONNECTIONS)) +

    (16000 bytes * Number of actual connections) +

    (256 bytes per connection per file actually opened))

Note the following points:

DAT_MEMORY and IDX_MEMORY defaults vary based on the type of Server (Standard vs. SQL) and the PAGE_SIZE. See "Basic Configuration Options" for details.
```
PAGE_SIZE <bytes>
```
The number of bytes per buffer page (maximum 65536 bytes). This value is rounded down to a multiple of 128. To encourage compatibility across different c-treeACE environments, we suggest not modifying the PAGE_SIZE. However, if performance is of concern, this value may be modified to suit the characteristics of the operating system. Generally, this is a matter to discuss with the application programmer.

A page size as low as 512 and 256 bytes are available with custom builds of c-treeACE

Default: 8192
```
IDX_MEMORY <bytes>
```
The memory allocated to the index cache, specified in bytes. Within the memory constraints of the hardware, there is no effective limit. High-speed buffer search routines ensure quick access to the entire cache.

Note: The default value for both the standard c-treeACE Server and the c-treeACE SQL Server is 600 * PAGE_SIZE. Assuming a default page size of 8192, the default DAT_MEMORY would be 4915200.

See Also
```
BUFR_MEMORY
```
```
DAT_MEMORY
```
```
TOT_MEMORY
```
```
USR_MEMORY
```
```
DAT_MEMORY <bytes>
```
The memory allocated to the data cache, specified in bytes. Within the memory constraints of the hardware, there is no effective limit.

Note: The default value for both the standard c-treeACE Server and the c-treeACE SQL Server is 600 * PAGE_SIZE. Assuming a default page size of 8192, the default DAT_MEMORY would be 4915200.

See Also
```
BUFR_MEMORY
```
```
IDX_MEMORY
```
```
TOT_MEMORY
```
```
USR_MEMORY
```
FILES defaults to 1000.
```
FILES <Number of Files>
```
The maximum number of data files and indices where each index, whether or not in a separate file, counts toward this total. For example, an index file which supports (i.e., contains as separate index members) three different keys counts as three files toward the FILES total. There is no effective limit to the number of files supported by the c-treeACE Server, except for any limits imposed by the available system memory.

Default: 100

See Also
```
MAX_FILES_PER_USER
```
CONNECTIONS default to 128.
```
CONNECTIONS <Number of Connections>
```
The maximum number of connections to the c-treeACE Server. Typically, c-treeACE Servers are activated to support up to one of the following values for concurrent user connections: 8, 16, 32, 64, 128, 256, 512, or 1024. However, your particular c-treeACE Server may be customized with a different value for connections. Specifying a number of users greater than the actual number of users needed results in inefficiencies (e.g., unused memory), so the goal is to keep this number as low as feasible on the system. The Activation Key flier displays the allowable number of users for your c-treeACE Server, as does the c-treeACE Server startup screen.

Default: Lower of 128 or activation limit
IDX_MEMORY is the MAX of:
- IDX_MEMORY or
- 3 * CONNECTIONS * (PAGE_SIZE + 400), where PAGE_SIZE defaults to 8K.

The following locking/transaction processing related items should be considered when approximating the c-treeACE Server dynamic memory requirements:

Each record locked consumes 24 bytes.

For transaction processing files only:

Each data record written consumes (record length + 42) bytes.
Each index operation consumes (key length + 42) bytes.

Note: Some operating systems offer virtual RAM (VRAM) which swaps data from memory to the hard drive. VRAM is usually automatically invoked if RAM gets full. Since data is being moved to and from the hard drive by VRAM, applications will often slow. If your system suddenly slows, examine this possible cause with your system administrator.