Re: Cluster File System Versus ASM for RAC Deployment in Production?... Pros & Cons

  • From: "LS Cheng" <exriscer@xxxxxxxxx>
  • To: mzito@xxxxxxxxxxx
  • Date: Fri, 7 Dec 2007 11:13:38 +0100

I had to setup OCFS2 in a customer for the these reasons:

they didnt want to assign a big lun for a small files such as voting and ocr

they used utl_file extensively, nfs was not an option because it would
become a SPOF

they didnt have a backup agent so backing up ASM to tape was not an option
and to to able to run backups from all fours nodes a CFS must be used



On 12/6/07, Matthew Zito <mzito@xxxxxxxxxxx> wrote:
> I always recommend using both ASM and a CFS, where appropriate.  For
> example, on Linux systems, where there is a free, Oracle-supported CFS
> (OCFS2), I recommend making a small OCFS2 filesystem (or two) for storage of
> OCR and voting files.  Then, make the primary datafile/index/log storage on
> ASM.  Optionally, they can then have a large dump or backup filesystem that
> is OCFS2, or NFS - but I always recommend keeping an archive location
> outside of ASM, so if the ASM instance won't start up, you can at least get
> to your archive logs, and presumably you're doing backups or a standby
> database somewhere.
> The reason for using both ASM and CFS on Linux is because dealing with
> multiple block devices for the various OCR and Voting devices is annoying
> and complex, and typically you'll end up wasting a lot of disk space (i.e.
> allocating an 8GB lun for a 100MB ocr device).  By using a clustered file
> system, you can put multiple objects on the one disk, and if necessary,
> store other things there.  However, OCFS2 has no capability for growing
> filesystems, creating situations where using OCFS2 for datafiles means
> increasing the number of mounts over time, which gets messy.  ASM solves
> that problem for you by doing very basic striping.
> Thanks,
> Matt
> --
> Matthew Zito
> Chief Scientist
> GridApp Systems
> P: 646-452-4090
> mzito@xxxxxxxxxxx
> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx on behalf of Dan Norris
> Sent: Thu 12/6/2007 7:51 AM
> To: VIVEK_SHARMA@xxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
> Subject: Re: Cluster File System Versus ASM for RAC Deployment in
> Production?... Pros & Cons
> Personally, I'd choose ASM and recommend it to all my customers. This is
> partly because: 1) Oracle recommends it, 2) if Oracle recommends something,
> they generally support it better than things they don't recommend, 3) it
> doesn't cost extra money, and 4) I think ASM is a fine product that does its
> job well (admittedly better in 11g than 10g, but that's not your question).
> I think that using a CFS requires training for system admins while ASM
> would also require training, but possibly for the DBAs instead of the
> sysadmins. Typically, I still see ASM being managed by DBAs even though it
> really isn't a database. Many companies have the DBAs manage anything with
> the word Oracle stamped on it.
> For docs or links, see
> Dan
> ----- Original Message ----
> From: VIVEK_SHARMA <VIVEK_SHARMA@xxxxxxxxxxx>
> To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
> Sent: Wednesday, December 5, 2007 9:08:21 PM
> Subject: RE: Cluster File System Versus ASM for RAC Deployment in
> Production?... Pros & Cons

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