Re: [Wrapper-user] how to prevent 2 instances of the same service running on 2 servers

[<da...@sm...>]

But one of the thoughts he had was to create the pid file on a network =20
accessable directory, so that both machines could use the same =20
physical location, and thus only one file existing.

Quoting Leif Mortenson <le...@ta...>:

> Martyn,
>     You would have to modify the shell script a bit.  But you could
> place the pid file
> mentioned in the shell script on the network share.  You would have to
> change the
> logic a bit however as the file is currently ignored if the process in
> the pid file does
> not exist.  It wouldn't exist on the other machine of course.
>
> Cheers,
> Leif
>
> Martynas Brijunas wrote:
>> Hi Leif,
>>
>> thank you for your answer.
>>
>> The processes are started manually by an operator. Or they can be
>> started automatically on one server, and manually on another. So that
>> would eliminate the problem of a power outage you mentioned.
>>
>> I was hoping that by detecting an existing PID file (for example, on a
>> network share), the wrapper would refuse to start on another server,
>> until this original PID file is removed.
>>
>> Martyn
>>
>>
>> 2006/7/10, Leif Mortenson <le...@ta...>:
>>
>>> Martyn,
>>>    The problem is that you are talking about two physical machines.
>>> The Wrapper has
>>> features do this within a single machine.  But not for multiple
>>> machines.  You will need to
>>> implement a startup class which say attempts to open a socket to the
>>> other machine.  If
>>> it connects, it knows the other server is running and shuts down.   If
>>> it fails to connect then
>>> it can assume it opens its own server socket to listen for connections.
>>>
>>>    This is not fail proof however.  You need to account for cases where
>>> both servers come
>>> up at pretty much the same instant.  Say after a power outage or
>>> something.   Maybe make
>>> server a the master.  It will always try to run.  Server B will try to
>>> start but then poll Server
>>> A and always shutdown if it finds it.  Something like that.
>>>
>>>    But like was already said, I don't think this is really under the
>>> scope of the wrapper
>>> unless I am missing what you are trying to say.
>>>
>>> Cheers,
>>> Leif
>>>
>>> Martynas Brijunas wrote:
>>>
>>>> Hi Martin,
>>>>
>>>> thank you for your reply. I think i explained the problem not  =20
>>>> very clearly.
>>>>
>>>> Server A: process AAA is running
>>>> Server B: process AAA must not be running if it is running on Server
>>>> A, otherwise it can.
>>>>
>>>> How to ensure that when it is running on Server A, it cannot be
>>>> started on Server B? And vice versa: when it is running on Server B,
>>>> it cannot be started on Server A.
>>>>
>>>> Is it possible to emply PIDs or anchor files for this purpose?
>>>>
>>>> Thanks,
>>>> Martyn
>>>>
>>>> 2006/7/7, Martin Gazak <ma...@mi...>:
>>>>
>>>>
>>>>> Hallo,
>>>>> this seems not to be a task for Java Service Wrapper - try to look for
>>>>> example at www.linux-ha.org (Linux/Unix environment only, but seems to
>>>>> be your case), you may achieve also failover of the service (including
>>>>> the IP failover).
>>>>>
>>>>>
>>>>>
>>>>> Martynas Brijunas wrote:
>>>>>
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> we have 2 servers that have the same wrapper services for failover
>>>>>> reasons. Only one instance of each server can run at any given time.
>>>>>> Is there a way to prevent an accidental start of a service in 2
>>>>>> locations? I thought of employing a PID file on a network share, but
>>>>>> not sure if that would work.
>>>>>>
>>>>>> Thank you.
>>>>>>
>>>>>>
>
>
>
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