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  • 1.  vSAN enabling existing cluster with existing used storage

    Posted Jul 28, 2015 11:57 PM

    Hi Guys,

    Fairly new to this.

    I'm vSAN enabling small existing cluster which has been used in a standard config so far. It consists of 3 hosts.

    I've added the required SSD storage to support vSAN and the SSD is discovered properly.

    I've enabled vSAN but vSAN cannot find any eligible HDD to include into the Network Partition. The existing HDD's are loaded with VMs.

    As it appears I completely misunderstood this. Do I need to have the disks completely formatted before adding them into the vSAN datastore?

    If so, would you recommend backing up the machines, formatting the HDDs, adding the vSAN and restoring back the VMs? - Any complications etc.

    Thanks in advance

  • 2.  RE: vSAN enabling existing cluster with existing used storage

    Posted Jul 29, 2015 02:43 AM

    yes, VSAN is going to be needing at least one SSD and at least one HDD drive (raw disk) attached with supported RAID controller to form disk group in VSAN clustered host. this needs to be fulfilled in your environment by adding at least one extra HDD per host basis, so you will see 3 eligible SSDs, along with 3 eligible HDDs. then go with Auto or manual disk group creation mode and your VSAN cluster will be formed. (I am assuming that, other requirements of VSAN like VSAN network creation etc are fulfilled)

    you can now do it phase wise, try to migrate some VMs from existing disks vsandatastore, and empty up this HDDs, add them in appropriate disk group, that way you vsandatastore will have more space to migrate other vms which are still there on existing VMFS datastore.

    I am suggesting this to avoid downtime, but in this case you will be needing at least 3 extra HDDs, 1 per esxi host.

    also remember when it comes to forming disk group in VSAN cluster, there is a need of having SSD space at least 10% or more of offered HDD space in the same disk group. and in a single disk group you can have 1 SSD and upto 7 HDDs. and upto 5 such disk groups per ESXi host in VSAN cluster.


    I have 2 HDDs, each of size 1 TB, to support these two HDDs in a single diskgroup I need at least 200 GB SSD.