=====Oracle ASM=====
====Removing ASM disks====

First you need to check what scsi disks are associated with it
<code>
[root@duboradb01uat ~]# multipath -ll mpathx
mpathx (360002ac000000000000006e90000cab7) dm-2 3PARdata,VV
size=1.0T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
`-+- policy='round-robin 0' prio=50 status=active
  |- 2:0:0:7  sdi                 8:128      active ready running
  |- 3:0:0:7  sdbg                67:160     active ready running
  |- 2:0:2:7  sdah                66:16      active ready running
  `- 3:0:2:7  sdcf                69:48      active ready running

</code>

then you remove the multipath device

<code>

[root@duboradb01uat ~]# multipath -f mpathy
</code>

Finally you remove all associated scsi disks

<code>
[root@duboradb01uat ~]# echo 1 > /sys/block/sdz/device/delete
[root@duboradb01uat ~]# echo 1 > /sys/block/sdbx/device/delete
[root@duboradb01uat ~]# echo 1 > /sys/block/sday/device/delete
[root@duboradb01uat ~]# echo 1 > /sys/block/sdcw/device/delete

</code>


====Checking ASM Disks====

Here are some commands to query the Oracle ASM disks

Disk links are located under 

  /dev/oracleasm/disks
  
To list the disks

  # oracleasm listdisks
  
To see if its a valid ASM disks

  # oracleasm querydisk -d ASM_DISK1
  
To map out the physical disks used by an OracleASM disk

  # oracleasm querydisk -p ASM_DISK1
  
====ASM Issues====

On the Oracle 7.1 cluser we had issues where oracle asm was not being loaded.

The file in /etc/udev/rules.d was fine but ASM was not starting. THe folder in /dev/oracleasm was not listed and there where no disks listed 

to resolve this we had to run the following commands

**  # oracleasm exit**
  
 ** # oracleasm init**
 
This creates the /dev/oracleasm folder but does not lists disks

 ** # oracleasm scandisks**

This creates the disk entries under /dev/oracleasm/disks

To see the entries use 
 

**  # oracleasm listdisks
**