Ocfs users - Jun 2004 - OCFS write/read across 2 nodes

Hi,

If I have ocfs on 2 nodes should I be able to do the following:

t=0
    Node A
        echo "1" > /ocfsmount/a

    Node B
        cat /ocfsmount/a
>>>>Question 1: At this point should I see "1"?
t=1
    Node A
        echo "2" > /ocfsmount/a

    Node B
        cat /ocfsmount/a
>>>>Question 2: At this point should I see "2"?
The problem is that at t=1 I am still seeing "1", however when I run
ocfstool on node B I can see "2".

Assuming that this is correct behaviour this must imply that Oracle writes
and reads to/from the filesystem in a different manner.
Is this where o_direct comes in?

Thanks
Dermot


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Yes. ocfs does not supported shared mmap. So what's happening is that
when you do the cat on node B in t1, the kernel does not read from the
disk, just from the buffer cache. odirect reads will read the correct
data.

On Tue, 2004-06-08 at 05:20, Dermot Reynolds wrote:
> Hi,
>  
> If I have ocfs on 2 nodes should I be able to do the following:
>  
> t=0    
>     Node A
>         echo "1" > /ocfsmount/a
>     
>     Node B
>         cat /ocfsmount/a
>  
> >>>>Question 1: At this point should I see "1"?
>  
> t=1    
>     Node A
>         echo "2" > /ocfsmount/a
>     
>     Node B
>         cat /ocfsmount/a
>  
> >>>>Question 2: At this point should I see "2"?
>  
> The problem is that at t=1 I am still seeing "1", however when I
run
> ocfstool on node B I can see "2".
>  
> Assuming that this is correct behaviour this must imply that Oracle
> writes and reads to/from the filesystem in a different manner.  
> Is this where o_direct comes in?
>  
> Thanks
> Dermot
>  
>  
>  
> 
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