Re: ASM and EMC PowerPath

  • From: Karl Arao <karlarao@xxxxxxxxx>
  • To: cichomitiko@xxxxxxxxx
  • Date: Sun, 10 Apr 2011 18:33:31 +0800

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 http://karlarao.tiddlyspot.com/index.html#ASMtoEMCPowerDevices
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
karlarao.wordpress.com
karlarao.tiddlyspot.com

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