Re: ASM and EMC PowerPath

From: Radoulov, Dimitre <>
Date: Sun, 10 Apr 2011 14:31:44 +0200
Message-ID: <>

Hi Karl,
thanks for the information (and thanks for adding partprobe to the list).

The report you mention reports DBSO1DATA1 with major/minor 8, 33 (ls -l /dev/oracleasm/disks).
This is the device sdc1 and emcpowerp is the logical path (the EMC Power path) to that device (if I understanding it right). But emcpowerp has different major/minor numbers, so I would expect to see its major/minor numbers,
if the disk is accessed through the emcpower path.

Of course, I could be totally wrong.

Could you please check if on the RAC you produced the report on, ORACLEASM_SCANORDER or ORACLEASM_SCANEXCLUDE are set in /etc/sysconfig/oracleasm?


On 10/04/2011 12:33, Karl Arao wrote:
> Hi Dimitre,
> See my answers below:
> 1) Question: which path should we use with the createdisk command?
> Answer: You should use the /dev/emcpowerz1 , note that as per the
> official doc you need to specify the whole disk partition
> 2) Question: Is the multipathing used , given querydisk -d returns the
> major/minor numbers of the phisical device?
> Answer: Kindly check on this wiki to know the mapping of ASM to EMC
> Power Devices
> This will show you a storage report that maps the relationship from
> the Oracle layer (ASM), Linux, and SAN storage. This info is very
> useful for you and the storage engineer. So you would know which is
> which in case of catastrophic problems..
> 3) Question: After adding and marking the disks for asm from one node,
> we'll need to run oracleasm scandisks on the remaining nodes,
> is it safe to run this command (scandisks) in a live production
> environment?
> Answer:
> - First you have to make a whole disk partition on that shared EMC
> Power Device on the 1st node, after doing that you have to
> issue "partprobe" (as root) on the remaining nodes
> - Second, you'll execute the "createdisk" on the 1st node... after
> that, you have to issue "oracleasm scandisks" on the remaining nodes
> - Third, you should verify on all the nodes by executing "oracleasm
> listdisks"
> Is it safe to do this? mmm.. I would allocate a window for doing this
> activity just to be safe.. or do it first on test environment or R&D
> machines..
> --
> Karl Arao
> <>
> <>

Received on Sun Apr 10 2011 - 07:31:44 CDT

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