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Not applicable

Cluster failover question

Dear Community

I am working at a customer where we have the problem that one very large application disturbs the performance for other smaller applications. For arguments sake lets call the large application App A and the small application App B.

App A: size 1 GB, used by 5 users

App B: Size 50 MB, used by 200 users

Our idea is to set up clustered QVS machines (QVS 1 and QVS 2) where App A is loaded on QVS 1 and App B is loaded on QVS 2, so far no problems.

Question 1: What happens if QVS 1 fails, will App A then load on QVS 2 although we have specified that App A is only loaded on QVS 1 or will App A upon not finding QVS 1 now load on QVS 2?

Question 2: Is there any documentation where these failover scenarios are described?

Best Regards

/Mats

18 Replies
Bill_Britt
Former Employee
Former Employee

HI Mats,

Yes, The load balancer is designed to check to see if the document is already open to put the user on the server that the document is loaded on. If not then open the document based on resources.

There is an option to "Document Available" that has to be set. You can also set a document to "Never" on a member of the cluster and that will stop the document from loading on that node.

Bill

Bill - Principal Technical Support Engineer at Qlik
To help users find verified answers, please don't forget to use the "Accept as Solution" button on any posts that helped you resolve your problem or question.
Not applicable
Author

Hi Bill

What I would like to do is to have the big App A loading only on QVS 1 and App B loading only on QVS 2 (so App A will be set to never load on QVS 2) but will that also be the case if then QVS 1 is down?

Best Regards

/Mats

Bill_Britt
Former Employee
Former Employee

If you set it to never, then it will never load on that node.

From the Help File

Document AvailableTo configure when the current document is to be available, select one of the following drop-down list options:

•Never, meaning that the current document will never be loaded on the node.

•Always, meaning that the document will always be available to be loaded on the node.

Bill

Bill - Principal Technical Support Engineer at Qlik
To help users find verified answers, please don't forget to use the "Accept as Solution" button on any posts that helped you resolve your problem or question.
korsikov
Partner - Specialist III
Partner - Specialist III

Hey. Does not work.

cluster on two node's 11.20.12354.0

That App A is available on the server QVS1 and AppB is available on both. Shutdown QVS1 server for the test. App A is not available in Access Point  error "No connection", does not run on QVS2. AppB work fine in both situation.

shane_spencer
Specialist
Specialist

It sounds like you have sacrifice resiliency for the sake of better performance (by pinning certain documents to a specific server). Perhaps this is something that Qlik need to work on, that in a failure scenario the pinned document will load on the resilient server.

i.e. Have a setting that states Load On Server 1 only. If Server 1 unavailable load on Server 2.

korsikov
Partner - Specialist III
Partner - Specialist III

yes, so goes Q cluster works. Really wanted to be that in case of failure of the first node of the cluster, the application will still run on the second node.

I did so.

preloading the application you chose for me the necessary node. And in web server chosen by balancing "Preloaded document". In the case when both nodes are available all works well. But in case of failure of such a situation comes.

example:

AppA reload in QVS1. All node run

If we connect to AccessPoint appA open in QVS1.

QVS1 falure

appA reconnect and open in QVS2.

QVS1 go

appA avalable preloaded in QVS1 and QVS2. load balance "Preloaded document"

in this case, on which server the document opens?

The experiments showed that opens on the server where this point was open session or most open sessions.

But then that did not work out as we need to. All documents are to work on the second server.

Not applicable
Author

Hi Alexander

so you tested this? It seems like you then actually need to redistribute the appA to QVS2 to make it work there?

Thanks a lot

/Mats

korsikov
Partner - Specialist III
Partner - Specialist III

how to make a distribution to one of the servers in the cluster? cluster uses a single shared storage. I need that to Annex A is always performed on one server, but in case of failure was available on other servers in the cluster. in our cluster is a server 2

Bill_Britt
Former Employee
Former Employee

Hi Mats,

I wanted to add this screen shot to show the correct setup for this.

cl.png

For the document to be load on server2 if server1 goes down the setting is Always. If you set it to Never the second server will never load it. Also, I have it set to Preload on Server1.

Bill

Bill - Principal Technical Support Engineer at Qlik
To help users find verified answers, please don't forget to use the "Accept as Solution" button on any posts that helped you resolve your problem or question.