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  • 1.  Local failures to tolerate in Stretched Cluster

    Posted Apr 12, 2022 03:42 PM

    Hello,

    I have a question about a Stretched cluster Failures to tolerate setting when creating a storage policy:

    _steez_0-1649777618893.png

     

    Do I need to tolerate any failures in Primary site? When testing failure scenarios - a host (containing VM data) was forsibly turned off, VMs still restarted on other host in the same site.

    What should be the optimal configuration in this scenario (4+4 hosts)? As selecting No data redudancy saves storage space masivelly. Only downsides I can think of is impacted network performance (as VM data now has to travel between sites).

    In what cases you would want to keep Failures to tolerate to RAID1/5 in stretched cluster deployments?



  • 2.  RE: Local failures to tolerate in Stretched Cluster
    Best Answer

    Posted Apr 19, 2022 07:25 AM

    It depends on your expectations. there's a big benefit to having local redundancy:

    • If a host fails and your VM is impacted read IO will still be from the local fault domain
    • rebuilds can happen from the local fault domain
    • you can withstand two failures across the fault domains, instead of 1

    but if you feel that you don't need that, or some VMs are less latency sensitive and a prolonged resync time doesn't matter, just go with no redundancy within the fault domain.