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.
[email protected] www.shapeblue.com 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue -----Original Message----- From: Jon Marshall <[email protected]> Sent: 23 May 2018 21:10 To: [email protected] 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 <[email protected]> Sent: 23 May 2018 19:55 To: [email protected] 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. [email protected] 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 <[email protected]> Sent: 23 May 2018 10:45 To: [email protected] 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 <[email protected]> Sent: Tuesday, May 22, 2018 8:28:06 PM To: [email protected] 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 <[email protected]> Sent: 22 May 2018 12:12 To: [email protected] 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 <[email protected]> Sent: Monday, May 21, 2018 8:36:04 PM To: [email protected] 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 [email protected] www.shapeblue.com<http://www.shapeblue.com> 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue [email protected] www.shapeblue.com<http://www.shapeblue.com> 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue
