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.an...@shapeblue.com www.shapeblue.com 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue -----Original Message----- From: Rohit Yadav <rohit.ya...@shapeblue.com> Sent: 23 May 2018 10:45 To: users@cloudstack.apache.org 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....@hotmail.co.uk> Sent: Tuesday, May 22, 2018 8:28:06 PM To: users@cloudstack.apache.org 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.ya...@shapeblue.com> Sent: 22 May 2018 12:12 To: users@cloudstack.apache.org 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....@hotmail.co.uk> Sent: Monday, May 21, 2018 8:36:04 PM To: users@cloudstack.apache.org 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.ya...@shapeblue.com www.shapeblue.com<http://www.shapeblue.com> 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue rohit.ya...@shapeblue.com www.shapeblue.com 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue
