Reliability, Scalability, And Disaster Recovery - Lexmark C792 Administrator's Manual

Reliability, scalability, and disaster recovery

The load balancer, database, and server components may be installed together on one computer or separately on
individual computers, depending on the demands placed on the system. However, a one-computer setup is subject
to down time if that computer fails, and the server load will be fairly limited. Ideally, a system has at least two server
computers connected to separate database and load balancer computers.
LDD is scalable to support a large number of clients submitting jobs to as many servers as required to handle the
load. The load balancer selects a server for each received job to distribute the total load and maintain system
performance. Using multiple servers also increases system reliability. If one server fails, the load balancer will direct
jobs to the other servers until the failed server is back online.
LDD uses a Tomcat Connector to manage load balancing in the system. The default balancing method is "Session,"
which estimates the number of sessions open by counting requests to the system that do not have a session cookie.
The session count is decayed by dividing in half, once per minute by default. The server with the lowest number of
estimated sessions is selected to process the request.
To further increase reliability by keeping the system online in the event of a failing load balancer or database, the
load balancer and database can each be paired in a failover cluster using a Microsoft Cluster Server (MSCS).
Solution
*.solution file
-Scripts
-Policy
Welcome Screen Layout
Device Settings
Solution Settings
Local
Global
-eSF
-3rd party jar files
-Status Page
LDD
Clients Group(s)
Device Group(s)
Lexmark Document Distributor overview
Adminstration
LMC
LDD
Server(s)
Load
Balancer
11
Data Base