By default, Lotus Notes Traveler allows an unlimited number of devices per user to connect to the Lotus Notes Traveler server. Many users will have multiple devices, a mobile phone and a tablet for example. In addition, you may want to allow users to "Bring Your Own Device" (BYOD), and therefore users may also
get their Personal Information Management (PIM) data on additional devices, such as their personal mobile phone, personal tablet, or devices owned by their spouse. Unregulated, this can present a multitude of problems for the Lotus Notes Traveler administrator and management. It will also have an impact on your server sizing and capacity planning, because the performance of a Lotus Notes Traveler server is affected by the number of active devices with which it has to synchronize, rather than the number of registered users. To help manage this, It is possible to optionally configure Lotus Notes Traveler to restrict the number of devices each user is permitted. As such, a decision should be made on the number of mobile devices you wish to allow per user.
If you want to maximize the number of users a single Lotus Notes Traveler server can support then set this number to one. If you are willing to provide additional server capacity to allow users to have multiple devices then you can set this number higher. A value of two would allow users to have both a smart phone and a tablet device. However be aware that in setting a device limit, there will be some overhead on your Lotus Notes Traveler administrators to manage requests from users who are changing or swapping devices as they won't be able to register their new device until their old one is either removed by an Administrator or automatically deleted after a period of inactivity to free up one of their permitted device quota. As such you may wish to consider setting the limit to 3 devices (or higher) so that a user can have 2 active devices at any one time plus a spare quota to allow the migration to a new device without having to request any administrator support. You also have the option of not setting any device limit at all, but be aware that in doing so you are allowing users to register as many devices as they wish which could cause issues with server performance and capacity planning as previously stated.
Administrators also must consider the amount of resources on the Lotus Notes Traveler server that will be consumed by each additional device. The addition of each device will require the use of more memory, processor cycles, and storage. A Lotus Notes Traveler server is limited to a finite number of devices it can handle, depending on the processors and memory on the server, and the amount of mail the users maintain on the device. Remember that this is a per mobile device resource, not per user and each device's state information is maintained separately by the Lotus Notes Traveler server from all the other devices owned by a user.
Each mobile device will also create a demand for services on the Lotus Domino Mail servers. When a mobile device connects to a Lotus Notes Traveler server, it will prompt the Note Traveler server to poll the Mail server every three seconds, by default settings, for any changes that needs to be synched with the mobile device. This is approximately the same amount of demand on the mail server as when a user connects directly to the mail server for their PIM data.
Each time a new device is registered, there is no additional polling required, but there will be additional load on the mail servers as these devices perform synchronization. So be aware that allowing users to have multiple devices will increase the load on your Lotus Domino Mail server as well.
Lotus Notes Traveler provides a setting that can be utilized to allow a device to connect only after approval from an administrator, or set to allow a certain number of devices for a user before approval is required for additional devices to connect. You can use these settings to help you manage how many devices a user can have configured for use with Lotus Notes Traveler. See section 8.2.2 Device settings
for information on how to set up a limit on the number of devices.
What does IBM do internally?
In the IBM internal implementation of Lotus Notes Traveler, users are not restricted on the number of devices they are allowed to use (i.e. users are permitted multiple devices). To accommodate this, the number of registered users each Lotus Notes Traveler server supports is less than its maximum so that there is spare capacity for users with multiple devices. On average, we see approximately 15% - 20% more devices on each server than we have registered users.