Sizing Guidelines

After determining the number of nodes and servers required, the information in this appendix can be used to arrive at memory and disk requirements.

Important points:

• A user uses approximately 2M of disk space per year.


• An active user requires 500K* of virtual memory. Hence, 500K of RAM per active user eliminates any swapping considerations, and no more than 500K of swap space per user is required.


• A directory entry, whether for a local user or a remote user, takes 1KB of disk space.

Determine Memory and Disk Requirements

To determine memory and disk requirements, the following guidelines should be followed:

Determine the amount of memory required per server. This is calculated by multiplying 500 KB by the number of logged-on users for the server. If the server will support more than one node, multiply 500 KB by the number of users for all nodes. Add an additional 32 MB for system use.

Determine the amount of permanent storage required per server. Each configured user requires approximately 2 MB of permanent storage. If the server will support more than one node, multiply 2 MB by the total number of users for all nodes. Add an additional 50 MB for product files and logs, and also add an appropriate amount for other storage not directly related to Netscape Calendar Server (i.e. operating system, system swap area, etc.).

Determine the amount of temporary storage required per server. This is calculated by multiplying 500 KB by the number of logged-on users for the server. If the server will support more than one node, multiply 500 KB by the number of users for all nodes.

The server has additional system-level storage and memory requirements which are not affected by the number of users. For planning purposes, each server will require 32 MB of extra memory and 50 MB of disk space. The disk space requirement is for Calendar Server software, including logs and executables. These numbers do not include operating system requirements which may vary by vendor.

Determine the number of spindles required per server. One spindle should be used per 100 active users for both permanent and temporary data. In other words, to support 100 users, one spindle for permanent data and one spindle for temporary data is recommended. This is a performance-related requirement to ensure that disk I/O is distributed across multiple drives. For optimal performance, three additional drives should be provided - one for the operating system, one for the operating system swap space, and one for the Calendar Server executables and logs.

The number of spindles for permanent and temporary storage have been established based on the Netscape recommendation that one spindle be used for each 100 active users for permanent data, and one spindle for each 100 active users for temporary data. A number higher than 100 may be used, with some degradation in performance; the higher the number of active users, the greater the performance degradation.

Finally, the size of the disks for permanent and temporary storage may be identified. For each server (or for each node if separate drives will be used for each node), divide the total disk requirements by the number of spindles.