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From הילה <>
Subject Re: Application crash after Migrate to different ESX
Date Tue, 17 May 2011 21:06:33 GMT
>>> I'll try explaining it differently.
>>>  we use smart keep alive with this application. the smart keep alive does
>> a
>> connection to the DB, query something that relates to the application, and
>> if everything turned out good, it returns state OK. if not ok, as in this
>> case, it returns error page 500 which means- unable to run the specified
>> query, because unable to connect to DB due to server side issue, or
>> because
>> DB unavailable and such.
>> so after migrate, it disconnect the users, and the keep alive is
>> unavailable
>> (page 500), then it's available (state ok), then after couple of seconds
>> again unavailable. then it returns to state ok and stay like this
>> (scenario
>> 1) or stays unavailable (page 500) until I restart the tomcat service and
>> then display state ok for good (scenario 2).
>>  ...
> I have no idea what this "smart keep alive" is, of which you talk above.
>  Is that a part of Tomcat ? If it returns an "error page 500", then it
> sounds more like a webserver in its own right.
> ..and also taking into account your other posts about this issue :
> We would of course try our best to help you here, but this is a mailing
> list dedicated to Tomcat, and it sounds as if the problem you are having is
> more about a more general problem of infrastructure and combining different
> pieces together, of which only one is Tomcat.
> I believe that questions and answers on this list are not the appropriate
> way to resolve that kind of problem, and I believe that what you really need
> is some expert help, from someone who really understands the different
> pieces and how they (should) fit together.
> Maybe these external consultants to which you referred ?
> To give you an idea : you said initially that the problem occurs when a VM
> is migrated (by Vmware) to another ESX server, and that when that happens
> the network connections are lost.  Well, I am not even sure that this is
> supposed to happen, if Vmware is configured correctly.  So you may be
> looking in the wrong place for a solution, to start with.
> better to call in an expert, you would probably save time and money in the
> end.
> I talked to VM experts, they say that network disconnection can happen for
> a sec, but the application shouldn't be affected by it as it is.
smart keep alive is a keep alive in its ordinary meaning. it called smart
cause it's not checking only the port and its availability, but also a
connection to the DB and functionality via DB query of some sort.
I do believe it relates to tomcat since in other machines that we migrated
and don't have tomcat, our application doesn't crash.
I also don't think this happened in every migrate we ever did. so I don't
understand why it began to happen.

the guys here in the list are helpful, so i'll give it a try. if no one can
help, i'll try different ways/methods/approach :]


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