tl;dr - your network config may result in a need for system VMs on both Xen and VMWare clusters.
Long form: System VMs provide services that are not feasible to deploy alongside the CloudStack management server. Currently, there are three kinds: secondary storage management services (aka SSVM), network services (aka virtual router), console services (aka console VM). Sanjeev makes the point that SSVM can provide zone-wide secondary storage management services. This SSVM has a light load, because it only setups up and manages images such as templates. The hypervisors access secondary storage directly when downloading images. In contrast, the virtual router's load and locality requirements may force CloudStack to create multiple instances. IIRC, this occurs when the virtual routers take on packet routing tasks as opposed to higher level services. IIRC, security groups are enforced by an on the hypervisor virtual router. If someone could comment on console VMs that would be great. Likewise, I would be interested to know if DHCP is zone wide or local to a hypervisor. > -----Original Message----- > From: Mike Tutkowski [mailto:mike.tutkow...@solidfire.com] > Sent: 18 July 2013 7:21 AM > To: dev@cloudstack.apache.org > Subject: Re: Quick Secondary Storage Question > > Thanks for your reply, Sanjeev! > > I was curious what the answer to that was (even though I realized after I sent > my e-mail why my system VMs weren't restarting and that it had nothing, as > you noted, to do with only having the XenServer system template). > > Thanks again! > > > On Thu, Jul 18, 2013 at 12:12 AM, Sanjeev Neelarapu < > sanjeev.neelar...@citrix.com> wrote: > > > Hi, > > > > If both the hypervisors are in the same zone , then you don't need to > > have the system templates installed for both hypervisor types. One > > system template should be fine. > > > > Thanks, > > Sanjeev > > > > -----Original Message----- > > From: Mike Tutkowski [mailto:mike.tutkow...@solidfire.com] > > Sent: Thursday, July 18, 2013 7:17 AM > > To: dev@cloudstack.apache.org > > Subject: Quick Secondary Storage Question > > > > Hi, > > > > I was wondering, if I am using two hypervisors (in my case, XenServer > > and ESXi), do I need to have the system template installed for both > > hypervisor types or will CloudStack function fine with having just one or > > the > other? > > > > I ask because I actually have a config with XenServer and VMware, but > > only have the XenServer system template on secondary storage because > > the VMware one was not working for me (some kind of a SOAP error when > > it was trying to deploy the template). > > > > I seem to be having trouble with system VMs not getting restarted, so > > I'm thinking it's because I don't have the VMware template on secondary > storage. > > > > Thanks! > > > > -- > > *Mike Tutkowski* > > *Senior CloudStack Developer, SolidFire Inc.* > > e: mike.tutkow...@solidfire.com > > o: 303.746.7302 > > Advancing the way the world uses the > > cloud<http://solidfire.com/solution/overview/?video=play> > > *(tm)* > > > > > > -- > *Mike Tutkowski* > *Senior CloudStack Developer, SolidFire Inc.* > e: mike.tutkow...@solidfire.com > o: 303.746.7302 > Advancing the way the world uses the > cloud<http://solidfire.com/solution/overview/?video=play> > *(tm)*
