Re: [ovirt-users] Autostart VMS

On Sat, Apr 9, 2016 at 12:07 AM, Brett I. Holcomb om> wrote: > > On Fri, 2016-04-08 at 21:50 +0300, Nir Soffer wrote: > > On Fri, Apr 8, 2016 at 9:33 PM, Brett I. Holcomb > com> > wrote: > > On Fri, 2016-04-08 at 19:25 +0300, Nir Soffer wrote: > > On Fri, Apr 8, 2016 at 7:17 PM, Brett I. Holcomb > com> > wrote: > > On Fri, 2016-04-08 at 11:31 +0200, Martin Sivak wrote: > > Hi, > > > I set highly available on, did not pin to any host, and also set > the > watchdog which should reset if they go down but I'm not sure that > will start > them if the host comes up and the VMs are not running.  I'll look > at the CLI > first. > > > The engine will try to keep the VM running. So if one host goes > down, > it will restart the VM on some other host automatically. We will > also > migrate the VM (or some other to free resources) when the current > host > gets too loaded. We do not require any migration addons, it just > works. But of course we have usually more hosts in a cluster to > make > this possible. > > I do not really remember what happens when all hosts are restarted > (power outage) though as that is quite special case. > > Regards > > -- > Martin Sivak > SLA / oVirt > > > > Thanks.  I only have one host so who knows what will happen.  I'm > working on > a script that will basically emulate what VMware does - start VMS > in a given > order at startup of the host/engine.  I'll also file a feature > request. > > > Why do you care about the order? > > Isn't it enough to restart all the vms after a host was restarted? > > Nir > > > Does the Engine start all VMs after the host is powered up and the > engine > running if I set a watchdog on a VM?  I know it will try to restart > the VM > if it goes down once oVirt is up and running.   If it will start > the VMs at > reboot time that helps. > > > I think only HA vms are restarted. Adding Michal to add more info > on this. > > > The reason for the order is that you need some servers such as DNS, > file > servers, up first before other systems can resolve addresses or > mount > shares.  For Windows you need domain controllers running before the > other > windows systems that are part of the domain.  For applications such > as Lotus > Notes the servers had to come up in the correct order. > > > Lets say you have a way to order the vms when some vms are down. > > What will happen to when dns, file servers or domain controller > will crash? > Do you have to restart all the vms depending on them or they can > recover and detect that vm they depend on were restarted? > > Seems that what you need is a systemd for your data center - every > host define the host it depends on, and the system generate the > correct order to start the vms, starting vms in the same time when > possible. > > Please reply also to the list, this thread may be useful to others. > > Nir > > > Hopefully this will go to the list as i"ve been making sure users@o > virt.org > is in the To field. > > I think we need to make sure we distinguish between the start up > phase and > the running phase which is what happens after everyone is up and > running > happily.  Based on my experience the crash of a server is > considered > separately from startup. > > As mentioned in my response to the list to someone else's comment > the > startup sequence is the same as people flipping switches on > physical servers > following a documented procedure to start or shutdown a datacenter > as we did > in the "old days".  With physical boxes we had to shutdown/startup > manually > and we did it in a sequence that we had written down.  With > virtualization > and since we had VMware we could automate that process so as we > spun up the > hosts VMware started spinning up the guests in the order specified > so we got > our DNS boxes up first, then others.  For Active Directory we > started the > domain controllers first, then other servers such as file servers, > application servers in the sequence needed for the applications to > run. > > Crashing of DNS, File Server, Domain Controllers crashing after the > datacenter is up and running is handled (or should be) by > redundancy of > servers or process the service provides.  You have multiple DNS > servers and > the resolver will try the secondary/tertiary/whatever if the > primary is > down.  File servers are the same.  For Gluster, CephFS, MS DFS you > have (or > should have setup) the ability to keep running if one of the > servers goes > down.  A redundant file server setup will handle a server > crash.  For Domain > Controllers you should have at least two (we had six in our > environment) and > when one goes down the others keep the domain running by shifting > the > services to others and continuing to provide authentication, > etc.  Generally > what we did when a domain controller crashed is fix it if possible > and if it > was not fixable pull it's pieces out of the domain and spin up a > new one. > Same for DNS or file servers.  When they go down find out why, fix > it or > replace the server, and get the service redundant again.  Also, > oVirt has > the watchdog function so if a VM goes down it will try and restart > it.  If > it can't restart then we're dealing with a crashed server which we > should > have provided for in our data center design. > > My wish is to have oVirt allow us to do what VMware does and allow > us to say > start/don't start these servers up in the order I specify so that > when the > Engine is ready it looks at the list and begins turning on VMs in > the order > specified.  Shutdown is done in the reverse order).  For large > datacenters > with many VMS manual startup is a pain.  Once it's running rely on > good > practices of having redundant servers (i.e. more than one DNS), > file servers > that can handle the failure of a server, multiple domain > controllers which > is not something we need to burden oVirt with.  Handling of > failures needs > to be done by the people in charge who are supposed to design the > data > center based on their risk/cost analysis. > > If I  understand what you said - I'm not sure we have to define a > dependancy > list where we define dependancies like we would with systemd or a > package > manger.  It doesn't need to be complex since just a simple list of > priority: > VM id/name pairs will work. All we need is to be able to say "start > these > VMs when the Engine is ready".  The order or dependency is set by > where I > put the VM in the list.  If it's at the top start it first, then > move to the > second one, and so on.  There can be settings for delay between > starting VMs > and how long to wait for a VM to come up before assuming it's dead > and > moving on to the next.  Tasking oVirt with the job of figuring VM > dependancies would be a nightmare for oVirt and whoever had to > program it > .  We as data center administrators should be handling that > task.  Yes, > we manually set the list but trying to automate a dependancy chain > would be > pretty difficult. > > I envision a web admin portal GUI where we define a simple list of > VMs that > we want the Engine to autostart. We need to be able to move them > up/down the > list.  The list is stored somewhere for the Engine (database?, > whatever else > the Engine has as storage areas - not really familiar with the > Engine > internals) and when the Engine is up and ready to start VMs it > retrieves the > list and starts at the first VM in the list and starts it, waits > some time > (0-?? seconds), and then moves on to the next one.  If the VM > hasn't started > in the set time the Engine moves on to the next one. > > Note that Microsoft's Hyper-V also provides automatic VM startup > but it is > done on a VM level where you just tell the VM to start whenthe > Hypr-V > starts.  If you want sequencing you have to set time > delays.  Auto  start up > is better than nothing but Hyper-V is a nightmare trying to > sequence VMs. > > I think VMware did it right in allowing both autostart and being > able to > sequence the startup of VMS so it's host independent.  As > information VMware > also allowed delays between VM startups as does Hyper-V. Thanks for the detailed description. Did you file a bug for this feature? Adding Moran and Doron. Nir > > On Wed, Apr 6, 2016 at 9:10 PM, Brett I. Holcomb > com> > wrote: > > On Wed, 2016-04-06 at 13:42 -0400, Adam Litke wrote: > > On 06/04/16 01:46 -0400, Brett I. Holcomb wrote: > > In VMware we could setup guests to autostart when the host started > and > define the order.  Is that doable in oVirt?  The only thing I've > seen > is the watchdog and tell it to reset but nothing that allows me to > define who starts up when and if they autostart.  I assume it's > there > but I must be missing it or haven't found it in the web portal. > > > In oVirt guests aren't tied to a host by default (although you can > set > them to run only on a specific host if you want).  The closest > thing I > can think of would be the High Availability features (VM->Edit). > oVirt will try to restart highly available VMs if they go > down.  You > can also set the priority for migration and restart in that pane. > Hopefully a combination of host pinning and the  high availability > settings will get you close enough to where you want to be. > > Otherwise, you could always do some scripting with the ovirt REST > API > using the SDK or CLI. > > > If you had the VMware migration extra add-on you could have hosts > move as > needed so they were not tied to any host either but we could set a > startup > order and specify auto, manual so that once the host started the > VMs were > brought up as specified no matter what host they were running on. > > I am running hosted-engine deployment with the Engine VM on the > host. > > I set highly available on, did not pin to any host, and also set > the > watchdog which should reset if they go down but I'm not sure that > will start > them if the host comes up and the VMs are not running.  I'll look > at the CLI > first. > > It would be nice if oVirt added this feature as it's really > required for > large installations and is a help for any size installation, even > small > ones. > > > > > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > > > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > > > _______________________________________________ > Users mailing list > Users(a)ovirt.org > http://lists.ovirt.org/mailman/listinfo/users >