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RE: 4.11 without Host-HA framework


I'm afraid that is not a host crash.  When shutting down the guest OS, the CloudStack agent on the host is still able to report to the management server that the VM has stopped.

This is my point. VM-HA relies on the management sever communication with the host agent.

Kind regards,

Paul Angus

paul.angus@xxxxxxxxxxxxx 
www.shapeblue.com
53 Chandos Place, Covent Garden, London  WC2N 4HSUK
@shapeblue
  
 


-----Original Message-----
From: Yiping Zhang <yzhang@xxxxxxxxxxx> 
Sent: 24 May 2018 00:44
To: users@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: 4.11 without Host-HA framework

I can say for fact that VM's using a HA enabled service offering will be restarted by CS on another host, assuming there are enough capacity/resources in the cluster, when their original host crashes, regardless that host comes back or not.

The simplest way to test VM HA feature with a VM instance using HA enabled service offering is to issue shutdown command in guest OS, and watching it gets restarted by CS manager.

On 5/23/18, 1:23 PM, "Paul Angus" <paul.angus@xxxxxxxxxxxxx> wrote:

    Hi Jon,
    
    Don't worry, TBH I'm dubious about those claiming to have VM-HA working when a host crashes (but doesn't restart).
    I'll check in with the guys that set values for host-ha when testing, to see which ones they change and what they set them to. 
    
    paul.angus@xxxxxxxxxxxxx 
    www.shapeblue.com
    53 Chandos Place, Covent Garden, London  WC2N 4HSUK
    @shapeblue
      
     
    
    
    -----Original Message-----
    From: Jon Marshall <jms.123@xxxxxxxxxxxxx> 
    Sent: 23 May 2018 21:10
    To: users@xxxxxxxxxxxxxxxxxxxxx
    Subject: Re: 4.11 without Host-HA framework
    
    Rohit / Paul
    
    
    Thanks again for answering.
    
    
    I am a Cisco guy with an ex Unix background but no virtualisation experience and I can honestly say I have never felt this stupid before 😊
    
    
    I have Cloudstack working but failover is killing me.
    
    
    When you say VM HA relies on the host telling CS the VM is down how does that work because if you crash the host how does it tell CS anything ? And when you say tell CS do you mean the CS manager  ?
    
    
    I guess I am just not understanding all the moving parts. I have had HOST HA working (to an extent) although it takes a long time to failover even after tweaking the timers but the fact that I keep finding references to people saying even without HOST HA it should failover (and mine doesn't) makes me think I have configured it incorrectly somewhere along the line.
    
    
    I have configured a compute offering with HA and I am crashing the host with the echo command as suggested but still nothing.
    
    
    I understand what you are saying Paul about it not being a good idea to rely on VM HA so I will go back to Host HA and try to speed up failover times.
    
    
    Can I ask, from your experiences, what is a realistic fail over time for CS ie. if a host fails for example ?
    
    
    Jon
    
    
    
    
    ________________________________
    From: Paul Angus <paul.angus@xxxxxxxxxxxxx>
    Sent: 23 May 2018 19:55
    To: users@xxxxxxxxxxxxxxxxxxxxx
    Subject: RE: 4.11 without Host-HA framework
    
    Jon,
    
    As Rohit says, it is very important to understand the difference between VM HA and host HA.
    VM HA relies on the HOST telling CloudStack that the VM is down on order for CloudStack start it again (wherever that ends up being).
    Any sequence of events that ends up with VM HA restarting the VM when CloudStack can't contact the host is luck/fluke/unreliable/bad(tm)
    
    The purpose of Host HA was to create a reliable mechanism to determine that a host has 'crashed' and that the VMs within it are inoperative. Then take appropriate action, including ultimately telling VM HA to restart the VM elsewhere.
    
    
    
    
    
    paul.angus@xxxxxxxxxxxxx
    www.shapeblue.com<http://www.shapeblue.com>
    Shapeblue - The CloudStack Company<http://www.shapeblue.com/>
    www.shapeblue.com
    ShapeBlue are the largest independent integrator of CloudStack technologies globally and are specialists in the design and implementation of IaaS cloud infrastructures for both private and public cloud implementations.
    
    
    
    53 Chandos Place, Covent Garden, London  WC2N 4HSUK @shapeblue
    
    
    
    
    -----Original Message-----
    From: Rohit Yadav <rohit.yadav@xxxxxxxxxxxxx>
    Sent: 23 May 2018 10:45
    To: users@xxxxxxxxxxxxxxxxxxxxx
    Subject: Re: 4.11 without Host-HA framework
    
    Jon,
    
    
    In the VM's compute offering, make sure that HA is ticked/enabled. Then use that HA-enabled VM offering while deploying a VM. Around testing - it depends how you're crashing. In case of KVM, you can try to cause host crash (example: echo c > /proc/sysrq-trigger) and see if HA-enabled VMs gets started on a different host.
    
    
    - Rohit
    
    <https://cloudstack.apache.org>
    
    
    
    ________________________________
    From: Jon Marshall <jms.123@xxxxxxxxxxxxx>
    Sent: Tuesday, May 22, 2018 8:28:06 PM
    To: users@xxxxxxxxxxxxxxxxxxxxx
    Subject: Re: 4.11 without Host-HA framework
    
    Hi Rohit
    
    
    Thanks for responding.
    
    
    I have not had much luck with HA at all.  I crash a server and nothing happens  in terms of VMs migrating to another host. Monitoring the management log file it seems the management server recognises the host has stopped responding to pings but doesn't think it has to do anything.
    
    
    I am currently running v4.11 with basic network but 3 separate NICs, one for management, one for storage and one for VMs themselves.
    
    
    Should it make it any difference ie. would it be worth trying to run management and storage over the same NIC ?
    
    
    I am just lost as to why I see no failover at all whereas others are reporting it works fine.
    
    
    Jon
    
    
    ________________________________
    From: Rohit Yadav <rohit.yadav@xxxxxxxxxxxxx>
    Sent: 22 May 2018 12:12
    To: users@xxxxxxxxxxxxxxxxxxxxx
    Subject: Re: 4.11 without Host-HA framework
    
    Hi Jon,
    
    
    Yes, Host-HA is different from VM-HA and without Host HA enabled a HA enabled VM should be recovered/run on a different host when it crashes. Historically the term 'HA' in CloudStack is used around high availability of a VM.
    
    
    Host HA as the name tries to imply is around HA of a physical hypervisor host by means of out-of-band management technologies such as ipmi and currently supporting ipmi as OOBM and KVM hosts with NFS storage.
    
    
    - Rohit
    
    <https://cloudstack.apache.org>
    [https://cloudstack.apache.org/images/monkey-144.png]<https://cloudstack.apache.org/>
    
    Apache CloudStack: Open Source Cloud Computing<https://cloudstack.apache.org/>
    cloudstack.apache.org
    CloudStack is open source cloud computing software for creating, managing, and deploying infrastructure cloud services
    
    
    
    
    
    
    ________________________________
    From: Jon Marshall <jms.123@xxxxxxxxxxxxx>
    Sent: Monday, May 21, 2018 8:36:04 PM
    To: users@xxxxxxxxxxxxxxxxxxxxx
    Subject: 4.11 without Host-HA framework
    
    I keep seeing conflicting information about this in the mailing lists and in blogs etc.
    
    If I run 4.11 without enabling Host HA framework should HA still work if I crash a compute node because my understanding was the new framework was added for certain cases only.
    
    It doesn't work for me but I can find a number of people saying you don't need to enable the new framework for it to work.
    
    Thanks
    
    Jon
    
    rohit.yadav@xxxxxxxxxxxxx
    www.shapeblue.com<http://www.shapeblue.com>
    53 Chandos Place, Covent Garden, London  WC2N 4HSUK @shapeblue
    
    
    
    
    rohit.yadav@xxxxxxxxxxxxx
    www.shapeblue.com<http://www.shapeblue.com>
    53 Chandos Place, Covent Garden, London  WC2N 4HSUK @shapeblue