[Linux-cluster] Linux-cluster Digest, Vol 70, Issue 9

[Muhammad Ammad Shah]

Hi Bob,

if we are running Database (oracle) on GFS on two node cluster, and if node(x) fenced, so this mean that there will be two problems. 

The node(x) File system (ext3)  /, /var/, /usr,.... can be crashed 
if the insertion was being running, then its lost. 

if i am right on this then its big problem to setup power fencing in critical environments. i think it should be some thing different like SAN data path fencing.

one more thing i want to know, if (oracle)node was running it was accessing the trace logs, control logs and ..... of oracle, then node(x) fenced and node(y) starts will it read from the old transaction point or it will be something else (i am not expert of oracle) .

 
Thanks,
Muhammad Ammad Shah
 




> From: linux-cluster-request at redhat.com
> Subject: Linux-cluster Digest, Vol 70, Issue 9
> To: linux-cluster at redhat.com
> Date: Mon, 8 Feb 2010 12:00:05 -0500
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>    1. Re: fencing node and filesystem (Bob Peterson)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Mon, 8 Feb 2010 09:49:34 -0500 (EST)
> From: Bob Peterson <rpeterso at redhat.com>
> To: linux clustering <linux-cluster at redhat.com>
> Subject: Re: [Linux-cluster] fencing node and filesystem
> Message-ID:
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> Content-Type: text/plain; charset=utf-8
> 
> ----- "Muhammad Ammad Shah" <mammadshah at hotmail.com> wrote:
> | Hi,
> | 
> | when a node(x) fenced by another node(y), will it corrupts the file
> | system or no? and if the database was running and node(x) fenced by
> | fenced node(y) will it corrupts the database or whats about the
> | transaction ?
> | 
> | 
> | 
> | Thanks,
> | Muhammad Ammad Shah
> 
> With GFS and GFS2 there should be no metadata corruption, in theory.
> When quorum is regained (or if it's not lost) the fenced
> node's journal is replayed so the file system metadata should
> remain intact.  That does not mean that data won't be lost.
> If the node was fenced while it had data in its cache, that data
> may be lost.  In critical situations, you can mark files and/or
> directories with a flag that makes the data journaled as well,
> so the data should be protected.  Of course, that has a performance
> penalty.  There's a small section about this in the GFS faq.
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems
> 
> 
> 
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