Oracle RAC and write to one remote File Server

[zooxmusic]

Hi all, I am wondering if an oracle rac can write to one remote file server machine. I am being told that this is not possible but it seems like a elementary task. Thanks for your help.

Brian

Spend like you don't need the money,
love like you've never been hurt and dance like nobody's watching!

 

[zooxmusic]

Sorry, I should say that I am being told that whatever node is active at that moment is where the file will be written to. i.e. If i am on server1 that is where my log is, if on server2 it would be there and on server3 it would be there. So I have a log file called queue.log and there are 3 different machines I have to go and look at these files to see where my log was written rather than writing to fileServer1 and all would write there.

Brian

Spend like you don't need the money,
love like you've never been hurt and dance like nobody's watching!

 

[karluk]

This is, indeed, a problem on certain types of RAC clusters. Ours is a typical example. We have a RAC cluster on HP-UX with all the shared disk on raw volume groups. If we want to write output to a flat file, we need to write it to a disk that is exclusively mounted on only one of the nodes in the cluster.

If a later job needs access to the file, this can present a problem. One way of handling this is to have the job that creates the file and all subsequent jobs that read it explicity log in to a specific instance. Then you will know that all the jobs have access to the same files. The disadvantage is that you lose some of the high availability that RAC is supposed to provide. If a node goes down jobs can fail, even if other nodes in the cluster are still up.

Another approach is to run an intermediate job after the first job finishes, which copies the file to all nodes of the cluster. Then the later jobs can run on any node and expect the file to be there.

I have heard that this issue isn't a problem if your RAC cluster supports a third party clustered file system. That would allow you to write log files and any other output to shared disk, where it will be accessible from all nodes in the cluster.

 

[zooxmusic]

Hi karluk, thanks for the response. Hmm, so if you just log say errors from the db, you have to search through machines and files to find all the logs?

Brian

Spend like you don't need the money,
love like you've never been hurt and dance like nobody's watching!

 

[karluk]

Exactly. A lot of this is normal behavior and shouldn't come as a surprise or create problems. For example, you will have not just one alert log, but one alert log for every instance in the cluster. If an error occurs that creates an alert log entry, it could be on any of the instances. You would have to check the alert logs on all the nodes to find the error, unless you happen to have additional information about where the activity occurred.

 

[zooxmusic]

The problem that seems to un-common to me is that my log is for my application. Not for an oracle instance. Actually I the real reason is because a package is used to write out a file that needs to be downloaded and instead of centralizing that file I am forced to keep multiple copies. This seems very wrong to me. Maybe you can set me straight on why there cant be a config file that all the instances share in which I can mount a \\fileserver\folder directory and they all write this particular .csv to this directory.

Brian

Spend like you don't need the money,
love like you've never been hurt and dance like nobody's watching!

 

[karluk]

Please reread my original response. We can't do this on our cluster because we are using raw disk for storage. If you are using a clustered file system, you can probably write your log to shared disk. Then you won't have this problem.