perfsonar development work

["Vedrin Jeliazkov" <>]

Hi Nicolas, All,

Support for perfSONAR service redundancy hasn't been much discussed up to now
AFAIK. This might make it rather tricky for quick implementation/deployment.

As far as perfsonarUI is concerned, we can imagine the following procedure:

1) LS provides info in some pre-defined and well known way whether a given
service has several instances and where they can be reached;

2) perfsonarUI randomly selects one of those instances and sends a query; if
the service returns some unexpected error or the query timeouts, then the
client asks another randomly chosen service instance; this process continues
until either the query is answered or the list of available service instances
is exhausted;

In fact, this pretty much follows the way how DNS stuff works.

Kind regards,
Vedrin

Nicolas Simar 
<>
 wrote:

> Hi,
> 
> for the deployment of the MDM service on GEANT, the DANTE operation team 
> mentioned that they would wish to have the services backup-ed on a 
> second server.
> 
> How can this be done? (a) for the next three months, (b) for the next 
> release?
> 
> 1) SSH telnet MP - two deployments each contacting the routers. No 
> issues foreseen.
> 
> 2) RRD MA - two deployments, how do they access the data? The original 
> DB might be on another server, how do you synchronize those? Do you 
> foresee another way of doing this?
> Obviously if the server where the original data are is down, we can't do 
> anything except if there are two instance capturing the data.
> 
> 3) L2 status MP - two deployments, each accessing the XML file stored 
> locally for one server, in another place for the other.
> Obviously if the server where the original data are is down, we can't do 
> anything except if there are two instance capturing the data.
> 
> 4) SQL MA - two deployments. What do you suggest to do with the DB? 
> Stored where? Any suggestions.
> 
> 5) LS - how two instance of the LS could have the same information? (can 
> the services register to two LSes at the same time)
> 
> 6) How would the LS advertise the fact that there are two web-services 
> offering the same information?
> 
> 7) How does the visualisation tools react to have two services offering 
> the same information? How would they react when one goes down?
> 
> Thanks a lot in advance
> 
> Cheers,