5 Replies Latest reply: Jan 15, 2014 6:00 PM by Hemant K Chitale

# Regarding Voting Disks

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From this article:http://dbarohit.blogspot.com/2012/12/why-oracle-recommends-voting-disks-in_25.html, it said 「A node must be able to strictly access more than half of the voting disks at any time」.

My question is Why it must be able to strictly access more than half of the voting disks at any time? In my RAC environment, if it exists only one voting disk or two voting disks, then what will be happen?

• ###### 1. Re: Regarding Voting Disks
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If a node cannot see at least half of the voting disks, it will never be able to win in a split brain scenario (which is resolved by nodes trying to reserve voting disks). If you only have a single voting disk and it fails - your cluster goes bye-bye. If you have an even number, what happens if 2 nodes each acquire exactly half - who wins?

• ###### 2. Re: Regarding Voting Disks
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>two voting disks

You wouldn't have two voting disks.  One, Three or Five.  That allows the surviving nodes to "hold" more than half the number of voting disks.  Those nodes that don't have more than half are "evicted".

Hemant K Chitale

• ###### 3. Re: Regarding Voting Disks
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If the number of voting disk is even number, that it would form split brain. So  the number of voting disk  should be an odd number. Isn't right?

• ###### 4. Re: Regarding Voting Disks
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If it is an even number, what would happen? Throw an error?

• ###### 5. Re: Regarding Voting Disks
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Oracle recommends an odd number.  I don't know what happens when you try to create an even number of voting disks -- this is when setting up the cluster, much before the question of a split brain condition arising.

Hemant K Chitale

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