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Re: RAC/CRS and OCFS2

From: Keith <kknauss_at_gmail.com>
Date: 15 Mar 2007 07:19:02 -0700
Message-ID: <1173968342.281186.130860@e65g2000hsc.googlegroups.com>


On Mar 15, 9:59 am, "hpuxrac" <johnbhur..._at_sbcglobal.net> wrote:
> On Mar 15, 9:50 am, "Keith" <kkna..._at_gmail.com> wrote:
>
>
>
> > Hello RAC gurus,
>
> > I am currently running 10.2.0.3 RAC/CRS on RHEL4. All our database
> > files are using ASM/raw devices. However, we now have the need for a
> > clustered file system. This file system likely would not be used
> > directly by the database, but requires high availability. So, we'd
> > like to use OCFS2 -- which has prompted some questions:
>
> > Are there any conflicts or issues with running OCFS2 and CRS
> > concurrently?
> > Can they share the same private interconnect?
> > Would this be an Oracle supported configuration?
> > If it is supported, ishttp://oss.oracle.com/projects/ocfs2/files/
> > Oracle's preferred place to obtain the software?
>
> > If OCFS2 panics the system (or anything "panics" the system), what is
> > the expected system behavior? (I'm curious if OCFS2 would ever prompt
> > or initiate a cluster node to be evicted/rebooted/etc).
>
> > Also, Metalink note 391771.1 discusses a bug that affects RHEL4 (fixed
> > in a later version than I'm running):
>
> > "Kernel panic - not syncing: ocfs2 is very sorry to be fencing this
> > system by panicing"
>
> > It gives the option of using the "DEADLINE" IO scheduler versus the
> > "CFQ" IO scheduler. Is there any impact associated with this change?
>
> > Any help is greatly appreciated. This came up on me very quick -- and
> > my 9i -> 10g migration is scheduled for next weekend. I'm in a pinch!
>
> You are planning on not only implementing 10g next weekend but also
> including a new clustered file system in an environment where you
> haven't done exhaustive testing ... I wouldn't worry if I were you!
>
> Opinions vary on ocfs2 but even some of the most devoted linux/oracle
> fans think it's something to run away from.
>
> If you really proceed down this path I would recommend using oracle
> consulting to install the OCFS2 and the 10g implementation so that you
> don't put your job on the line.

Well, the RAC/CRS has been tested thoroughly; but the OCFS2 is the new requirement. As I started to read the OCFS2 users guide, I become very wary b/c of the OCFS2 "cluster services" -- I'm concerned they may interfere with CRS. If OCFS2 is not the way to go, are there better, proven alternatives? RH GFS?

If it helps any, I have two RAC nodes tapping into an EMC storage array. On one node I have a file system built that will be NFS'd out to several "client" systems (in support of an old web technology that I'm not sure when will be replaced). Management would like this file system "clustered" for high availability. Which raises more questions:

If I NFS mount a clustered file system, can I only NFS mount from one of the nodes?
If so, should that node go down, would I still lose the NFS mount and be forced to remount from a surviving node? Is there likely an "online" and quick method to re-present the disk (say, from the SAN side) to the surviving node and mount the file system there (so as to avoid using a clustered file system altogether)? Received on Thu Mar 15 2007 - 09:19:02 CDT

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