Project No. 9

Salone Gupta Amartya DasguptaSyed Eqbal AlamSneha Maria JosephArijit Mitra

High Availability???A system design that ensures certain degree

of operational continuity.Provides fault toleranceProvides data reliability

Virtual machine migration

Virtualization???

Goals

1. Implementation of active and passive servers on a virtual platform

2. Implementation of a heartbeat mechanism3. Implementation of process image transfer

for keeping track of data4. Implementation of switching mechanism

between active and passive servers

Low Level Architecture

Active Server

Physical Machine

HeartbeatModule

Image TransferModule

Virtual Machine

Physical Machine

Passive Server

Virtual Machine

Image TransferModule

Terminal ServerHeartbeatModule

Client

1

2

HeartbeatModule

Client Reconnector

4

6

5

7

3

Workflow WHEN THE ACTIVE SERVER IS WORKING1. The client requests the terminal server.2. The terminal server checks the heartbeat signals from the active server.3. If the heartbeat signal is ok, the client request is redirected to the active

server.4. After the request acknowledgement, the active server sends its image and

process checkpoint to the passive server at a certain frequency.

WHEN THE ACTIVE SERVER FAILS5. The terminal server pings the passive server to check its health status and the

passive server restarts from the previously received image and process checkpoint.

6. The terminal server redirects the client to the passive server.a. Now the passive server starts behaving as the active server and when the

previously failed active server is restored it behaves as a passive server i.e. the roles interchange.

b. The passive server now sends heartbeat signals to the terminal server to notify its health status.

7. The passive server sends its image and process checkpoint to the restored active server.

On the advent of another failure the steps are repeated and the roles again interchange.

Module DescriptionImage Transfer module – Salone Gupta and Amartya

DasguptaCreation of image of the server and the process checkpoint

associated with a client requestHeartbeat module – Arijit Mitra

Sends or receives a heartbeat signal or ping to notify or to check the health of a server.

Also used to check available passive servers in a passive server cluster.

Client Reconnector – Syed Eqbal and Sneha Joseph Client connection and redirection to the active and passive

servers.Server Setup – Salone Gupta, Arijit Mitra and Amartya

DasguptaSetup an active server and a passive server.Setup a terminal server for client reconnection.

Integration – Team

Implementation Plans1. Setup of the active, passive and the terminal

servers as virtual machines using Xen/Vmware.2. Using the heartbeat mechanism, the terminal

server checks the status of the other active servers.

3. Process transfer will be implemented by creating process checkpoints using an open source tool.

4. On the advent of failure, switching between active and passive servers will controlled by the terminal server.

Progress Till DateCheckpoint creation and restart on single

system using an open source tool “BLCR” - Berkeley Lab Checkpoint/Restart

Partial heartbeat implementation

Plans Ahead

Deliverables on March 9th,2009 Virtual server setup Client connection to the servers

Referenceshttp://www.ftg.lbl.gov/checkpoint (Berkeley

Lab Checkpoint/Restart) http:// www.ultramonkey.org http:// www.keepalived.org Remus virtualization projecthttp://www.eukhost.com/server-mirroring.ph

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