Hi Tim, As long as it work, since it's only used to for the initial instruction set at the VR boot so eth0 can be configure, I think xenstore would work just fine. unless you are saying we could just not rely on xenstore in terms of reliability?
*Pierre-Luc DION* Architecte de Solution Cloud | Cloud Solutions Architect t 855.652.5683 *CloudOps* Votre partenaire infonuagique* | *Cloud Solutions Experts 420 rue Guy *|* Montreal *|* Quebec *|* H3J 1S6 w cloudops.com *|* tw @CloudOps_ On Fri, Jan 12, 2018 at 7:34 PM, Tim Mackey <tmac...@gmail.com> wrote: > > We found that we can use xenstore-read / xenstore-write to send data from > dom0 to domU which are in our case VRs or SVMs. Any reason not using this > approach ? > > xenstore has had some issues in the past. The most notable of which were > limitations on the number of event channels in use, followed by overall > performance impact. iirc, the event channel stuff was fully resolved with > XenServer 6.5, but they do speak to a need to test if there are any changes > to the maximum number of VMs which can be reliably supported. It also > limits legacy support (in case that matters). > > Architecturally I think this is a reasonable approach to the problem. One > other thing to note is that xapi replicates xenstore information to all > members of a pool. That might impact RVRs. > > -tim > > [1] "xenstore is not a high-performance facility and should beused only for > small amounts of control plane data." > https://xenbits.xen.org/docs/4.6-testing/misc/xenstore.txt > > On Fri, Jan 12, 2018 at 4:56 PM, Pierre-Luc Dion <pd...@cloudops.com> > wrote: > > > After some verification with Syed and Khosrow, > > > > We found that we can use xenstore-read / xenstore-write to send data from > > dom0 to domU which are in our case VRs or SVMs. Any reason not using > this > > approach ? that way we would not need a architectural change for > XenServer > > pods, and this would support HVM and PV virtual-router. more test > required, > > for sure, VR would need to have xentools pre-installed. > > > > > > *Pierre-Luc DION* > > Architecte de Solution Cloud | Cloud Solutions Architect > > t 855.652.5683 > > > > *CloudOps* Votre partenaire infonuagique* | *Cloud Solutions Experts > > 420 rue Guy *|* Montreal *|* Quebec *|* H3J 1S6 > > w cloudops.com *|* tw @CloudOps_ > > > > On Fri, Jan 12, 2018 at 4:07 PM, Syed Ahmed <sah...@cloudops.com> wrote: > > > > > KVM uses a VirtIO channel to send information about the IP address and > > > other params to the SystemVMs. We could use a similar strategy in > > XenServer > > > using XenStore. This would involve minimal changes to the code while > > > keeping backward compatibility. > > > > > > > > > > > > On Fri, Jan 12, 2018 at 3:07 PM, Simon Weller <swel...@ena.com.invalid > > > > > wrote: > > > > > > > They do not. They receive a link-local ip address that is used for > host > > > > agent to VR communication. All VR commands are proxied through the > host > > > > agent. Host agent to VR communication is over SSH. > > > > > > > > > > > > ________________________________ > > > > From: Rafael Weingärtner <rafaelweingart...@gmail.com> > > > > Sent: Friday, January 12, 2018 1:42 PM > > > > To: dev > > > > Subject: Re: [DISCUSS] running sVM and VR as HVM on XenServer > > > > > > > > but we are already using this design in vmware deployments (not sure > > > about > > > > KVM). The management network is already an isolated network only used > > by > > > > system vms and ACS. Unless we are attacked by some internal agent, we > > are > > > > safe from customer attack through management networks. Also, we can > (if > > > we > > > > don't do yet) restrict access only via these management interfaces in > > > > system VMs(VRs, SSVM, console proxy and others to come). > > > > > > > > > > > > > > > > Can someone confirm if VRs receive management IPs in KVM deployments? > > > > > > > > On Fri, Jan 12, 2018 at 5:36 PM, Syed Ahmed <sah...@cloudops.com> > > wrote: > > > > > > > > > The reason why we used link local in the first place was to isolate > > the > > > > VR > > > > > from directly accessing the management network. This provides > another > > > > layer > > > > > of security in case of a VR exploit. This will also have a side > > effect > > > of > > > > > making all VRs visible to each other. Are we okay accepting this? > > > > > > > > > > Thanks, > > > > > -Syed > > > > > > > > > > On Fri, Jan 12, 2018 at 11:37 AM, Tim Mackey <tmac...@gmail.com> > > > wrote: > > > > > > > > > > > dom0 already has a DHCP server listening for requests on internal > > > > > > management networks. I'd be wary trying to manage it from an > > external > > > > > > service like cloudstack lest it get reset upon XenServer patch. > > This > > > > > alone > > > > > > makes me favor option #2. I also think option #2 simplifies > network > > > > > design > > > > > > for users. > > > > > > > > > > > > Agreed on making this as consistent across flows as possible. > > > > > > > > > > > > > > > > > > > > > > > > On Fri, Jan 12, 2018 at 9:44 AM, Rafael Weingärtner < > > > > > > rafaelweingart...@gmail.com> wrote: > > > > > > > > > > > > > It looks reasonable to manage VRs via management IP network. We > > > > should > > > > > > > focus on using the same work flow for different deployment > > > scenarios. > > > > > > > > > > > > > > > > > > > > > On Fri, Jan 12, 2018 at 12:13 PM, Pierre-Luc Dion < > > > > pd...@cloudops.com> > > > > > > > wrote: > > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > > > We need to start a architecture discussion about running > > SystemVM > > > > and > > > > > > > > Virtual-Router as HVM instances in XenServer. With recent > > > > > > > Meltdown-Spectre, > > > > > > > > one of the mitigation step is currently to run VMs as HVM on > > > > > XenServer > > > > > > to > > > > > > > > self contain a user space attack from a guest OS. > > > > > > > > > > > > > > > > Recent hotfix from Citrix XenServer (XS71ECU1009) enforce VMs > > to > > > > > start > > > > > > > has > > > > > > > > HVM. This is currently problematic for Virtual Routers and > > > SystemVM > > > > > > > because > > > > > > > > CloudStack use PV "OS boot Options" to preconfigure the VR > > eth0: > > > > > > > > cloud_link_local. While using HVM the "OS boot Options" is > not > > > > > > accessible > > > > > > > > to the VM so the VR fail to be properly configured. > > > > > > > > > > > > > > > > I currently see 2 potential approaches for this: > > > > > > > > 1. Run a dhcpserver in dom0 managed by cloudstack so VR eth0 > > > would > > > > > > > receive > > > > > > > > is network configuration at boot. > > > > > > > > 2. Change the current way of managing VR, SVMs on XenServer, > > > > > potentiall > > > > > > > do > > > > > > > > same has with VMware: use pod management networks and assign > a > > > POD > > > > IP > > > > > > to > > > > > > > > each VR. > > > > > > > > > > > > > > > > I don't know how it's implemented in KVM, maybe cloning KVM > > > > approach > > > > > > > would > > > > > > > > work too, could someone explain how it work on this thread? > > > > > > > > > > > > > > > > I'd a bit fan of a potential #2 aproach because it could > > > facilitate > > > > > VR > > > > > > > > monitoring and logging, although a migration path for an > > existing > > > > > cloud > > > > > > > > could be complex. > > > > > > > > > > > > > > > > Cheers, > > > > > > > > > > > > > > > > > > > > > > > > Pierre-Luc > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > Rafael Weingärtner > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > Rafael Weingärtner > > > > > > > > > >
