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MIVA^®  RESOURCES:  NT Empresa On Multiple Servers

Marcus Tettmar, 11/30/2000

Hi Ivo,

I'm a colleague of Richard Heaton who communicated with you a few weeks ago asking for advice on record locking on NT and getting Miva working on multiple IIS servers, with the miva database residing on a network share, in order to facilitate load balancing / redundancy.

I spent a good few days looking for a solution to the multi-server issue and finally found one. I am forwarding you an email to miva technical support which explains how I solved this. I thought you might find it useful, and may want to include it on your web site. If you need more detail, please let me know.

Kind regards,
Marcus

Hi,

When I set Miva's data directory to a network path, Miva says it can't find the data directory. I have ensured that the permissions on the directory and the share are ok, and I also tried restarting IIS (web publishing service).

Please help - I need to put the database on a network storage device for increased reliability - the redundant server will also connect to that.

Thanks!
Marcus

Hello Marcus,

As this has not been tested, and is not a standard installation method, we do not support using a shared network folder as the data directory. You may want to consult our user groups to see if anyone has sucessfullyinstalled in this method, and if they can offer any advice. Here is a link to the user groups: http://www.miva.com/support/usr_grps/.

Damon, Miva Technical Support

Hi,

I appreciate that it has not been tried and is therefore not supported by yourselves.

However, I would really appreciate understanding whether or not this is even feasible from a technical point of view - i.e. what is the software doing internally when it is allocating the directory - does it do it on IIS startup? Does it look at what type of drive it is and decide how to use it (i.e. could it be that it refuses to use network drives at all?). What security permissions etc are required and so on. I have tried it out myself and got no-where, and have followed it up with some users who believe it might be possible and at least one who claims he has got it to work sometime in the past, but whose advice has yielded no success.

What would be really useful for me is if I could have 20-30 minutes of a lead developer's time to discuss this issue. Rather than spend more time trying this out and talking to other users, this time could be saved by knowing whether or not it is even worth trying and understanding how Miva works - if you see what I mean.

My client is desperate for a solution where we can put miva data on a network share.

Many thanks for your time,
Marcus

Hi,

Just to let you know that I have found a solution for this. So no urgency now. I am now able to get Miva to use a network directory as it's data directory. :-) The solution is actually very simple as all these things are when it finally occurs to you, and I am happy to let you know how I resolved this if it would be of use to you in the future.

However, I would still be interested to get some information on how Miva handles XBase record locking.

Thanks,
Marcus

I would LOVE to know.
I will put some information together on Database locking. And send it later on today.

Thanks!

Jeremy, Miva Technical Support

Well, I've spent a week looking into this on and off, and now I'm kicking myself. :-) It was while trawling through the Microsoft Knowledge Base on network share issues that I found this article: Q124184 - "Service Running as System Account Fails Accessing Network".

Of course - IIS is the one that runs miva and tries to access the share. IIS is running as a service. Services by default run as the system user. System users, as they run before the system is fully loaded, have no credentials - they are "null sessions". They have no username or password associated with them. Therefore a network share will not permit them access!! All along it never occured to me that this was the problem - it is nothing to do with Miva really!

Some services allow you to specify which user to run them as. Unfortunately the IIS service (Web Publishing Service) only allows you to run it as system.

However, Q124184 explains how to edit the registry on the machine that the shared resource is on to tell it to allow null sessions to access that resource. As explained in Q124184, on the machine that has the share, you edit the registry key as follows:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters\NullSessionShares

And edit NullSessionShares to include the name of the share you want to give the null session access to.

restart the web server, and IIS now has access to the share, so Miva won't complain when using that share as the data directory :-)

Hope this is useful.

Regarding file locking - I'm being asked to see if it is possible to load balance Miva. Now that I can get miva talking to it's database on a network share, the only issue left is whether or not there will be a problem with file locks. The answer depends on how Miva handles the record locking. I wouldn't have thought it would be a problem, as I've used many XBase databases in the past like this, with multiple separate instances of the program accessing them. However, I'm going to run some simple test scripts to ensure I don't get any problems writing data from two web servers, and any info you can provide would be most useful.

Of course, I am aware that you don't support this configuration so I/we won't come running to you if there is a problem - I have made the company aware of this. But any info you can send me to help me in my analysis of this issues would be very much appreciated.

If there is an issue and it turns out we can't have even load balancing, at least now we can still have redundant servers and use the load balancer only to bring in the redundant server should the first fail, so this is already a great result. :-)

Thanks,
Marcus

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