Evidian
RATP – Paris subway
Profile• RATP manages the Parissubway, transporting
more than 10 million
passengers every day.
Users
• Subway line 1 is totally
automated anddriverless.
Challenges• To ensure highavailability for thecentralized commandroom (CCR) of line 1 ofthe Paris subway.
Benefits• Software cluster
deployment on
standard servers.
• The same highavailability solution on
Windows and Linux.
• A solution comprisingload balancing, failover
after incident and realtime data replication.

RATP chose the SafeKit high availability and load balancing solution forthe centralized control room of line 1 of the Paris subway.
Monitoring a totally automated, driverless subway line

The centralized control room (CCR) of a subway line is a hub of critical activity. Theoperators managing the line must react immediately to the slightest incident. The
idea of an IT failure compromising the operators’ view of the line’s activity is totallyunthinkable.
The operators monitor movements on the subway tracks, process automatic door
closure incidents via video cameras and provide safety information to passengers
via the PA systems. A system of Windows and Linux gateways accessing theequipment (tracks, video, radio, etc.), based on a core and DBMS, manages andstores information. A web front-end presents this information to the operators.

A built-in high availability solution

RATP’s project management had high availability requirements for the CCR
supervision system for line 1. The project manager, Stéphane Guilmin, was facedwith major constraints: he was subject to strict scheduling requirements, and most of
the applications to be taken into account were not initially designed to run in thismode.
Among the possible solutions, the SafeKit software had already proved its value toRATP, having been implemented in the CCR of line 4. However, RATP’s newautomation project for line 1 had additional constraints: the subway line to bemonitored would be totally automated and driverless.
Hardware solutions (shared disk on a SAN, load balancing network box) werequickly eliminated because they were too expensive, difficult to configure andrelatively inflexible. SafeKit was chosen because the product appeared to be simpler
to implement on standard servers, easy to administrate– the same consol manages
both Windows and Linux servers – and versatile. It ensures load balancing,automatic application recovery and real time data replication.

Case study > Transport

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Implementation of SafeKit clusters at the RATP

In practice, the deployment of SafeKit consisted in a functional definition stage,
followed by a SafeKit configuration for each protected application. The actual
applications were not modified. SafeKit does not require any physical modificationon the servers it manages. RATP was able to use standard hardware, thereby
reducing its costs and minimizing the impacts of project implementation.

“Automation of line 1 of theParis subway is a major
project for RATP, requiring acentralized command room(CCR) designed to resist ITfailures.
With SafeKit, we have three
distinct advantages to meetthis need.
Firstly, SafeKit is a purely
software solution that does
not demand the use ofshared disks on a SAN andnetwork boxes for loadbalancing. It is very simple
to separate our servers into
separate machine rooms.
Moreover, this clusteringsolution is homogeneous for
our Windows and Linux
platforms.
SafeKit provides the threefunctions that we needed:load balancing between
servers, automatic failover
after an incident and realtime data replication.”
Stéphane Guilmin,Project manager,RATP.

A SafeKit application cluster has two servers with the same operating system, anapplication installed on these two servers, which also run SafeKit and one or more
“application module(s)”.
An application module is a high availability and load balancing configuration
package, adapted to the characteristics of a given application. Several application
modules can be run in parallel on the same cluster to optimize power use of the twoservers.
RATP uses two types of clustering on line 1’s CCR:
• The active / active farm cluster, which provides network load balancing andautomatic failover in the event of a failure• The active /passive mirror cluster, which provides real time data replication
and automatic failover in the event of a failure
The applications for the CCR of line 1 were delivered one after another according toa pre-defined schedule. Evidian's professional service developed the SafeKit
application modules for each of the applications. RATP validated the deliveries on its
three infrastructures: tests, pre-production and production. This organization
minimized dependency during the project and meant no impact on application
developments.

Daily use of the solution

The IT operators of the line 1 CCR can now administrate all their application clusters
using the same tool, the same configuration, the same on-line commands and thesame administration console. Indeed, SafeKit works in the same way on Windowsand Linux, and uses the same console to monitor load balancing, high availability
and data replication.
The backup servers of the numerous critical applications are in a separate machineroom and run on separate power supplies. In the event of an incident, operation cancontinue without loss of service for the passengers of the Paris subway.

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