2 Replies Latest reply on Sep 9, 2019 4:50 AM by depping

    Some basic question on VSAN

    zeelee Lurker

      Hi everyone,

      I am new Vm ware, I have some basics questions:


      Let say we have three ESXi : ESXi-1, ESXi-2, ESXi-3


      1)All three ESXi are using vSAN. Let say VM files associated with VM3 on ESXi-3 are being stored on VSAN, more specifically, in the memory on ESXi-1.which ESXi-1 is contributing for vSAN. Given the above scenario, what happen if ESXi-1 goes down? Will VM3 still able to function ?


      2) Let say we want to do Cluster HA for VM , Vmotion,  can we do it with vSAN? My concern is with vSAN, if ESXI ,which is contributing towards vSAN storage, goes down, all the VM files stored on ESXI will be lost ,as a result those affected VM will not be able to function.


      Thanks and have a good night!!

        • 1. Re: Some basic question on VSAN
          IRIX201110141 Master

          vSphere HA is a requirement for vSAN. When ever a Host goes down the VM will crash and HA tries to restart the VM on  one of the other remaining Hosts. How can it be? Because vSAN use FTT=1 as default which means all Data are stored as RAID 1 so there is a copy of the data on one of the other Hosts.


          FTT=1 ends in one copy of the data on two hosts and one whitness. This explains why the technical minimum of 3 hosts are needed.


          yellow-bricks.com have a lot of stuff about vSAN and there is also a vSan Deep Dive book.




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          • 2. Re: Some basic question on VSAN
            depping Champion
            User ModeratorsVMware Employees

            There are hundreds of articles on this topic. As mentioned my blog has many, but also cormachogan.com and for instance storagehub.vmware.com has loads of information to cover these basic questions. In short, what you are asking is possible. By default vSAN will store multiple copies of your data, so if 1 host disappears for whatever reason then there's still 1 copy available, which means that HA can restart the VM.

            1 person found this helpful