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Add new multipath disk to ASM Diskgroup

A Multipath disk provide failover by using redundant physical path components,  eliminating a single point of failure with the Storage Area Network (SAN). Multipathing is a software technology implemented at the operating system device driver level.

With ASM, you can ensure the discovery of a multipath disk by setting the value of the initialization parameter ASM_DISKSTRING equal to the name of the pseudo device that represents the multipath disk.

Below steps can be followed to add a new disk to ASM Disk Group.

 

STEP 1) CHECK CURRENT DISKS

 

 

 

STEP 2) CHECK ASM TO PHYSICAL DISK MAPPING

If you have not documented earlier which ASM disk is mapped to which physical disk and what all free disks you have in your server, your need t firs find out this information.

Use asm querydisk command first with every ASM disk name:

 

Now use multipath -ll to check corresponding multipath disk and what all disks are free in your server.

 

 

Looking at the above two outputs we can find out which ASM disk is attached to what physical disk

For example DB_DATA02 (on /dev/sdm) is attached to Physical multi disk path mpath18.

mpath24 can be seen as free physical disk which is not linked to any ASM disk yet.

 

STEP 3) PARTITION THE DISK

We will use the free disk /dev/mapper/mpath24

 

 

 

 

 

 

STEP 4) CREATE ASM DISK

 

Run below command on all database nodes (if using RAC):

 

The new disk should be visible from all database nodes now.

Now we have ASM disk ready to be added to ASM Disk Group

 

STEP 5) ADD ASM DISK TO DISKGROUP

Check Current Status >

 

As you can see that the new disk’s status is showing as ‘PROVISIONED’.

NOW ADD NEW DISK :

You can verify the rebalancing operation by below SQL command.

 

 

STEP 6) CHECK NEW STATUS

 

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Brijesh Gogia

I’m an experienced Oracle Applications DBA with more than a decade of full-time DBA experience. I have gained a wide knowledge of the Oracle software stack and have worked on several big projects for multi-national companies. I enjoy working with the leading-edge technology and have passion for database performance and stability. Thankfully my work allows me time for researching new technologies (and to write about them).
  
You can connect with me on LinkedIn.

2 Comments

  1. Vishwanath K Vishwanath K

    Thanks Brijesh……thank you for sharing this post its really helpful

  2. Anonymous Anonymous

    Its a wonderful post, I ever read.
    Thanku so much.

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