Maintenance Manual

Chapter 2 Fault Tolerance
Historical Data Servers
2-20
Cisco ICM Enterprise Edition Administrator Guide Release 6.0(0)
If the site has two Distributor AWs, Client AWs are configured to automatically
switch to a secondary Distributor AW if the first distributor becomes
non-functional for any reason. The secondary Distributor AW also maintains
connections to the real-time server; however, these connections remain idle until
needed.
You specify whether to install Distributor or Client AWs through the ICM Setup
tool.
Historical Data Servers
Historical data is forwarded to the Distributor AW where they are stored in a
special database. The distributor then acts as an Historical Data Server (HDS) for
the admin site. Admin Workstations at the site query historical data from the HDS
rather than directly from the Logger.
Two Distributor AWs at a site are set up as HDS machines. Each has its own HDS
database. The same fault-tolerant strategy that applies to the real-time Distributor
AW also applies to the HDS. That is, when the primary HDS fails, other Admin
Workstations at the site automatically switch over to use the backup HDS.
The “Historical Data Server” section in Chapter 4, “Database Administration,”
provides more information on setting up an HDS AW.
Simplexed Operation
If you have a simplexed Central Controller configuration, you are vulnerable to a
single device failure (for example, a system failure, process failure, or a disk
crash). You should have a strategy in place for keeping daily backups of the
central database. Your backup strategy might involve regularly scheduled
backups, mirrored disk configurations, or Redundant Array of Inexpensive Disk
(RAID) configurations. You should always have the central database backed up
on removable media.
If the central database becomes unavailable due to disk failure, contact your ICM
support provider. A support representative can assist you in replacing the disk,
rebuilding the database, and restoring the configuration and historical data.
For more information on database backup and restore procedures for simplexed
Central Controllers, see Chapter 5, “General Administration.”