HPE SimpliVity

Lost storage/federation network - SVT Behavior

 
steez
Advisor

Lost storage/federation network - SVT Behavior

Hello,

I am currently working on HA whitepaper about the Simplivity.

I have a question about the OVC behaviour where:

Switched 2 node cluster loses storage and federation network. Management network is still up meaning that the Arbiter sees both nodes. What is the outcome of this situation?

Will the Arbiter kill one of the hosts and VMs will restart on the Arbiter decided "Master" host?

5 REPLIES 5
gustenar
HPE Pro

Re: Lost storage/federation network - SVT Behavior

The arbiter won't "kill" any host as it isn't one of its functions. If storage and fed network is lost in a host but the svtfs service is still running, you will see alerts that "Simplivity Datastores Access Impaired" most likely. If the svtfs service is down then that's different, the OVC will failover and ownership of the VMs will change. 

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tonymcmillan
Frequent Advisor

Re: Lost storage/federation network - SVT Behavior

In this scenario, both hosts are healthy, they just can't replicate the VMs they're hosting. So, the hosts should continue to run their respective running VMs but you won't have replicated copies of the VMs across both hosts. When the network issue is resolved, the hosts will re-sync the VM data and you have true HA status.

The Arbiter should be keeping track of which host owns each VM and has the latest data for it. 

steez
Advisor

Re: Lost storage/federation network - SVT Behavior

Hello, and thank you for responses @gustenar @tonymcmillan, great information, that clarifies some things.

I am now confused about other thing - hypothetically if I have storage and federation link loss that means that VMs are no longer being synced, but everything stays up. 

What if one of the hosts suddenly dies? Then VMs will HA restart on other available host unsynced with old data causing a data loss/coruption? What is the behavior then?

I know that this is very unlikely, but you know the saying if it can go wrong it will go wrong.

tonymcmillan
Frequent Advisor

Re: Lost storage/federation network - SVT Behavior

Losing sych traffic and then a host which has running VMs on it fails is a real scenario.

I too wonder how this system is programmed to deal with this scenario. 

Is anyone from HPE able to shed light on this?

steez
Advisor

Re: Lost storage/federation network - SVT Behavior

bump