Re: Oracle RAC and OGFS

Oracle since around verison 8.x has its own built-in DLM (not unlike
openDLM) for managing shared access to the database blocks of database
tables stored in tablespaces stored in OS files or raw partitions. Pre
version 8.x the h/w vendor had to provide the DLM and for IBM's
clusters, they shipped what became openDLM. Then Oracle sucked their own
DLM into the core database and made it a standard.

Oracle does direct IO to OS files. Best not to get in Oracle's way. The
benefit of ocfs is that it gives a file system name to otherwise raw
partitions and so simplifies management of the database's data by
supplying a modified fileutils package that supports normal file like
management of the database files. But ocfs is not a general purpose
cluster file system and can't be used for executable or config files
located in ORACLE_HOME for example. For that you'd want to use a real
Posix cluster file system.

How many nodes will openGFS run on now?

Thanks,
Robert


>>> [email protected] 04/23/04 5:32 PM >>>
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Greg,
You obviously know some of the shortcomings of ogfs, so I don't need to
go 
into those with you.

I'm not sure what Oracle does in the case where it is on a fs that
supports 
locks. I know it uses it's own internal locking when using ocfs or raw 
partitions. If it uses it's own locking on ogfs, then you should be okay

performance wise (or if there is a way to make it use it's own locking).
If 
it tries to use the fs locking, you are going to be hurting. I'm not
really 
sure how to go about finding that out, but if it does try to use the fs 
locking, the thing to do would probably be to use ogfs for the control
files, 
etc. Then use raw partitions for the actual db. At least that's probably
what 
I would do.

- --Brian Jackson

On Friday 23 April 2004 5:48 pm, Greg Freemyer wrote:
> All,
>
> Has anyone tried Oracle RAC (9i or 10g) with ogfs?
>
> I want to put together a low-cost solution for experimenting with
Oracle
> RAC?
>
> Also, since Oracle has its own lock manager for internal DB locking
> issues, is there any reason to think ogfs would have anything but good
> performance?
>
> ie. I think most of the ogfs performance issues revolve around
> functionality the Oracle would not use.
>
> Also, I know ocfs (Oracle Cluster File System) is available as GPL,
but
> I don't think it has a lock manager at all, so it can only hold the
> database itself, not any of the associated programs and control files.
>
> That does not sound very friendly to me.
>
> Thanks
> Greg

- -- 
http://www.brianandsara.net
For Sale : http://www.brianandsara.net/temp/forsale.php
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