[Ocfs-users] Observations

[Sunil Mushran]

> 1. TIME STAMP Issue 
OCFS changes the mtime only if the file meta-data is changed. This
includes a extend/truncate of the file or a simple touch. Other local
filesystems update mtime during every write. As ocfs is a clustered
system, updating time or any meta-data changes, requires a cluster wide
lock, which is an expensive operation. So, we avoid that during writes.
So, this has nothing to do with RAC.... just a filesystem behavior.

> 2. COPY / FTP Issue
That's why we provide the o_direct enabled fileutils. As this is a
clustered fs, the data blocks are being updated by different nodes.
To ensure a consistent view of the file, one should always use the
o_direct flag inorder to bypass the possible stale data in that
node's buffer cache.

On Mon, 2004-08-30 at 12:50, Varghese Abraham wrote:
> Hi,
>  we have a 2 node / 3 node RAC installation with OCFS.
> We have the following observations.
> 
> 
> 1. TIME STAMP Issue 
> 
> We have noticed that the time stamp which is shown on the datafiles doesnt remain the same even after a shutdown normal /shutdown immediate
> 
> i.e If I shutdown all RAC instances ( A , B , C) using shutdown normal / immediate, the timestamp on the datafiles are not the same.
>  Even If I just bring up one node ( Say A ) and shut it down normally, after doing an Alter system checkpoint,
>  I still dont see same time stamp on all the datafiles.
> 
> (  I did an alter system checkpoint on a non-rac database and I noticed that all the datafiles changed the time stamp to the current timestamp)
> 
> Is this expected behaviour from a RAC database on OCFS. ?
> 
> 
> 2. COPY / FTP Issue
> 
>  We tried to clone from a RAC to a NON-RAC database using a cold backup of the RAC Instance.
>  On once occasion  we used simple copy command (cp)  to copy the files over to ext3 disk
>  On the second occasion we used ftp command in bin mode to ftp the files over to the destination node to ext3 disk.
> 
> On both occassions while creating the new control file on Target node, we got error stating the System file needs more recovery. ( Althoug we are 100% sure that on both occassions databases were shutdown normally for the backup)
>  
> On both above mentioned ocassions we were able to correct the problem using cp --o_direct command to copy the files over.
> When we used cp --o_direct , we were able to create the Target Database successfully.
> 
> Has anyone noticed any similar issue with copy / ftp. ?
>   
> 
> R'gds
> Varghese Abraham.
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