RE: Voting Disks and OCR on

From: John Hallas <>
Date: Wed, 21 Nov 2012 17:19:54 +0000
Message-ID: <>

I agree entirely Jed - I am happy with external redundancy as I accept the storage layer provides redundancy, however for such things as voting disks and redo logs (which are both very small relative to overall database sizes) then I would certainly advocate mirroring whenever possible.


-----Original Message-----
From: [] On Behalf Of Walker, Jed S Sent: 19 September 2012 16:56
To:; Zabair Ahmed Cc:
Subject: RE: Voting Disks and OCR on

I wouldn't rely on the storage mirroring for the voting disk. I would have it redundant within Oracle also - as you would for controlfiles, online redo logs, etc. I have seen it happen before where a flaw in the mirroring technology resulted in the loss of a file. The system had been created with single online redo logs because the disk was mirrored, but the mirroring failed and the database failed with it.

-----Original Message-----
From: [] On Behalf Of Radoulov, Dimitre Sent: Wednesday, September 19, 2012 5:07 AM To: Zabair Ahmed
Subject: Re: Voting Disks and OCR on

On 19/09/2012 12:58, Zabair Ahmed wrote:
> So, back to my original question. Do I have a single point of failure?
> I have single raw/block device LUN which is configured within ASM as
> an ASM diskgroup (ASMSYS) with EXTERNAL REDUNDANCY to hold a single
> Voting Disk. At the SAN level I am told by the sysadmin that it's
> either RAID 1 or RAID 5.

So it appears that your single voting disk is on a mirrored LUN (RAID 1 or 5), I don't consider this a single point of failure.




Wm Morrison Supermarkets Plc is registered in England with number 358949. The registered office of the company is situated at Gain Lane, Bradford, West Yorkshire BD3 7DL. This email and any attachments are intended for the addressee(s) only and may be confidential. 

If you are not the intended recipient, please inform the sender by replying to the email that you have received in error and then destroy the email. 
If you are not the intended recipient, you must not use, disclose, copy or rely on the email or its attachments in any way. 

This email does not constitute a contract in writing for the purposes of the Law of Property (Miscellaneous Provisions) Act 1989.

Our Standard Terms and Conditions of Purchase, as may be amended from time to time, apply to any contract that we enter into. The current version of our Standard Terms and Conditions of Purchase is available at:

Although we have taken steps to ensure the email and its attachments are virus-free, we cannot guarantee this or accept any responsibility, 
and it is the responsibility of recipients to carry out their own virus checks. 
Received on Wed Nov 21 2012 - 18:19:54 CET

Original text of this message