Although UNIX and D3 are virtual machines, they can run using a small amount of physical memory.
The use of physical memory affects system performance. System performance can be considerably improved by increasing the amount of physical memory, so the processes do not frequently swap out to disk, a condition known as thrashing.
D3 and UNIX can also share memory resources to help alleviate this potential problem. However, the best way to avoid this performance bottleneck is to ensure that there is an adequate amount of physical memory.
This calculation is used to estimate the optimal amount of physical memory:
Physical memory = UNIX system memory + UNIX users
+ D3 monitor memory + D3 shared memory (core)
+ D3 FlashBASIC users (BASIC) + (UNIX-to-D3 users * 260 KB)
| Parameter | Description |
|---|---|
| UNIX system memory | Memory required by the UNIX kernel and base system processes. |
| UNIX users | Amount of memory used for each UNIX user (such as users who
do not log on to D3) running concurrently. This amount varies widely,
so it cannot be fully taken into consideration here. Shared memory and physical memory requirements of the users must be determined as well as the physical memory requirements of the users. A good rule of thumb is to have at least 1 MB per UNIX user. |
| D3 monitor memory | Memory required by the D3 Monitor. Approximately 700 KB (local data and stack). |
| D3 shared memory (core) | See Shared memory usage. |
| FlashBASIC users (BASIC) | See Shared memory usage. |
| UNIX-to-D3 users | Maximum number of users who log in to UNIX first, then execute
D3. On D3 turnkey systems, D3 users bypass UNIX and log on to D3 directly, so this value would be zero. |
Use this worksheet to calculate minimum physical memory requirements:
| UNIX System Memory | ||||||
| UNIX Kernel | ||||||
| UNIX Users | _______ | * 260 KB | ______ | |||
| Total UNIX System Memory | ______ | |||||
| D3 Shared Memory | ||||||
| D3 Monitor Memory | 700 KB | |||||
| D3 Shared Memory (core) | _______ | |||||
| D3 Shared Memory (BASIC) | _______ | |||||
| UNIX to D3 Users | _______ | * 260 KB | _______ | |||
| Total D3 Shared Memory | ________ | |||||
| TOTAL PHYSICAL MEMORY | ________ | |||||