vSAN1

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  • 1.  vSAN Explaination

    Posted Dec 23, 2014 10:41 AM

    Hi,

    I'm looking for an explanation as to how vSAN works.

    I understand we need a minimum of 3 host and this uses raid 1. what does the third host do?

    Cheers,

    Jon



  • 2.  RE: vSAN Explaination

    Posted Dec 23, 2014 11:47 AM

    A good start to find information about VSAN is http://www.yellow-bricks.com/virtual-san/. I'm no salesman, but in this case I can highly recommend the "Essentials Virtual SAN" book - written by Cormac Hogan and Duncan Epping - for which you can find a link on the URL I mentioned.

    André



  • 3.  RE: vSAN Explaination

    Posted Dec 23, 2014 10:17 PM

    PCPUK wrote:

    Hi,

    I'm looking for an explanation as to how vSAN works.

    I understand we need a minimum of 3 host and this uses raid 1. what does the third host do?

    Cheers,

    Jon

    The third host is a witness to prevent a split brain scenario.

    Say you have a network connectivity issue where one host can't communicate with the other two.  Synchronizing of data can no longer occur between the two hosts so one host has to be chosen to serve up and write the data to. The group that has greater than 50% of the storage objects communicating will be chosen to continue to host the data.  This wouldn't work with an even number of hosts.

    You can read more about it here VSAN Part 21 – What is a witness? | CormacHogan.com

    I also recommend Cormac and Duncan's book.