RE: [libvirt] pausing / unpausing guests with libvirt

21 Sep 2008

...
Is it possible you could isolate whether the problem is with libvirt
or with the Java bindings?  One way would be to shell out to 'virsh'
just to see if virsh fails to change the state (ie. a libvirt/C) or if
the problem is in the Java bindings.
Pausing/resuming Xen domains is a very common and well-tested
operation so I would be surprised if it's a libvirt problem, but you
never know ...
Using following C code does not work.  The domain starts but does not
suspend.  When I call virConnGetLastError() error->code is 0 and
error->message is NULL.  I ran my code with LIBVIRT_DEBUG=1.  The output is
below the C code.

I was able to suspend the guest with virsh.  The guest was started with my C
code below.  You should be able to suspend the guest at any point, correct?

virsh # suspend 65
DEBUG: libvirt.c: virDomainLookupByID (conn=0x882f208, id=65)
DEBUG: hash.c: __virGetDomain (New hash entry 0x8846808)
DEBUG: libvirt.c: virDomainSuspend (domain=0x8846808)
Domain 65 suspended
DEBUG: libvirt.c: virDomainFree (domain=0x8846808)
DEBUG: hash.c: virUnrefDomain (unref domain 0x8846808 Linux2 1)
DEBUG: hash.c: virReleaseDomain (release domain 0x8846808 Linux2)
DEBUG: hash.c: virReleaseDomain (unref connection 0x882f208 xen:/// 2)

Thanks
-matthew

#include <stdio.h>
#include <unistd.h>
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>

const char* xml =
"<domain type='xen'>"
"<name>Linux2</name>"
"<os>"
    "<type>hvm</type>"
    "<loader>/usr/lib/xen/boot/hvmloader</loader>"
    "<boot dev='hd'/>"
"</os>"
"<memory>500000</memory>"
"<vcpu>1</vcpu>"
"<on_shutdown>shutdown</on_shutdown>"
"<on_reboot>restart</on_reboot>"
"<on_crash>restart</on_crash>"
"<features>"
    "<pae/>"
    "<acpi/>"
    "<apic/>"
"</features>"
"<devices>"
    "<emulator>/usr/lib/xen/bin/qemu-dm</emulator>"
    "<input type='tablet' bus='usb'/>"
    "<graphics type='vnc' autoport='yes' listen='192.168.1.226'/>"
    "<serial type='pty'/>"
    "<disk type='block'>"
        "<source dev='/dev/vgvms/Linux2'/>"
        "<target dev='hda'/>"
    "</disk>"
    "<interface type='bridge'>"
        "<mac address='D6:5F:DF:05:45:BB'/>"
        "<source bridge='Bridge2'/>"
    "</interface>"
"</devices>"
"</domain>";

int main (int argc, char** argv) {
    virConnectPtr conn;
    virDomainPtr dom;

    if (virInitialize () < 0) {
        printf ("virInitialize() failed\n");
        return -1;
    }

    conn = virConnectOpen ("xen:///");
    if (!conn) {
        printf ("virConnectOpen() failed\n");
        return -1;
    }

    dom = virDomainDefineXML (conn, xml);
    if (!dom) {
        printf ("virDomainDefineXML() failed\n");
        return -1;
    }

    if (virDomainCreate (dom) < 0) {
        printf ("virDomainCreate() failed\n");
        return -1;
    }

    sleep (30);

    if (virDomainSuspend (dom) < 0) {
        virErrorPtr error = virConnGetLastError (conn);
        printf ("virDomainSuspend() failed: %d\n", error->code);

    }

    sleep (60);

    if (virDomainResume (dom) < 0) {
        printf ("virDomainResume() failed\n");
    }
    return 0;
} 

[root@grape tmp]$ ./a.out
DEBUG: libvirt.c: virInitialize (register drivers)
DEBUG: xen_internal.c: xenHypervisorInit (Using new hypervisor call: 30001
)
DEBUG: xen_internal.c: xenHypervisorInit (Using hypervisor call v2, sys ver3
dom ver5
)
DEBUG: libvirt.c: virConnectOpen (name=xen:///)
DEBUG: libvirt.c: do_open (name "xen:///" to URI components:
  scheme xen
  opaque (null)
  authority (null)
  server (null)
  user (null)
  port 0
  path /
)
DEBUG: libvirt.c: do_open (trying driver 0 (Test) ...)
DEBUG: libvirt.c: do_open (driver 0 Test returned DECLINED)
DEBUG: libvirt.c: do_open (trying driver 1 (Xen) ...)
DEBUG: xen_unified.c: xenUnifiedOpen (Trying hypervisor sub-driver)
DEBUG: xen_unified.c: xenUnifiedOpen (Activated hypervisor sub-driver)
DEBUG: xen_unified.c: xenUnifiedOpen (Trying XenD sub-driver)
DEBUG: xen_unified.c: xenUnifiedOpen (Activated XenD sub-driver)
DEBUG: xen_unified.c: xenUnifiedOpen (Trying XS sub-driver)
DEBUG: xen_unified.c: xenUnifiedOpen (Activated XS sub-driver)
DEBUG: libvirt.c: do_open (driver 1 Xen returned SUCCESS)
DEBUG: libvirt.c: do_open (network driver 0 Test returned DECLINED)
DEBUG: libvirt.c: do_open (network driver 1 QEMU returned DECLINED)
DEBUG: remote_internal.c: doRemoteOpen (proceeding with name = xen:///)
DEBUG: libvirt.c: do_open (network driver 2 remote returned SUCCESS)
DEBUG: libvirt.c: do_open (storage driver 0 Test returned DECLINED)
DEBUG: libvirt.c: do_open (storage driver 1 storage returned DECLINED)
DEBUG: libvirt.c: do_open (storage driver 2 remote returned SUCCESS)
DEBUG: libvirt.c: virDomainDefineXML (conn=0x92ae478, xml=<domain
type='xen'><name>Linux2</name><os><type>hvm</type><loader>/usr/lib/xen/boot/
hvmloader</loader><boot
dev='hd'/></os><memory>500000</memory><vcpu>1</vcpu><on_shutdown>shutdown</o
n_shutdown><on_reboot>restart</on_reboot><on_crash>restart</on_crash><featur
es><pae/><acpi/><apic/></features><devices><emulator>/usr/lib/xen/bin/qemu-d
m</emulator><input type='tablet' bus='usb'/><graphics type='vnc'
autoport='yes' listen='192.168.1.226'/><serial type='pty'/><disk
type='block'><source dev='/dev/vgvms/Linux2'/><target
dev='hda'/></disk><interface type='bridge'><mac
address='D6:5F:DF:05:45:BB'/><source
bridge='Bridge2'/></interface></devices></domain>)
DEBUG: xend_internal.c: xenDaemonDomainDefineXML (Defining w/ sexpr:
(vm (name 'Linux2')(memory 488)(maxmem 488)(vcpus 1)(uuid
'5d9f6df2-6930-b2b8-4f71-db8575faa3ae')(on_poweroff 'destroy')(on_reboot
'restart')(on_crash 'restart')(image (hvm (kernel
'/usr/lib/xen/boot/hvmloader')(vcpus 1)(boot c)(acpi 1)(apic 1)(pae 1)(usb
1)(usbdevice tablet)(parallel none)(serial pty)(device_model
'/usr/lib/xen/bin/qemu-dm')))(device (vbd (dev 'hda:disk')(uname
'phy:/dev/vgvms/Linux2')(mode 'w')))(device (vif (mac
'd6:5f:df:05:45:bb')(bridge 'Bridge2')(script 'vif-bridge')))(device
(vkbd))(device (vfb (type vnc)(vncunused 1)(vnclisten '192.168.1.226')))))
DEBUG: libvirt.c: virDomainLookupByName (conn=0x92ae478, name=Linux2)
DEBUG: hash.c: __virGetDomain (New hash entry 0x92bd1e0)
DEBUG: libvirt.c: virDomainCreate (domain=0x92bd1e0)
DEBUG: libvirt.c: virDomainSuspend (domain=0x92bd1e0)
virDomainSuspend() failed: 0
...
-----Original Message-----
From: Richard W.M. Jones [mailto:rjones@redhat.com] 
Sent: Friday, September 19, 2008 2:21 PM
To: Matthew Donovan
Cc: libvir-list@redhat.com
Subject: Re: [libvirt] pausing / unpausing guests with libvirt
...
I'm working on a management application that will control 
Xen guest vms
(HVMs) with libvirt Java bindings.  I want to be able to
On Fri, Sep 19, 2008 at 09:23:52AM -0400, Matthew Donovan wrote:
pause and unpause
...
the VMs but doing so through the libvirt functions does not 
seem to actually
pause the VM.  The suspend function returns true and 
doesn't throw any
exceptions, however, the guest VM is still running and responsive.
Any pointers are greatly appreciated.
Is it possible you could isolate whether the problem is with libvirt
or with the Java bindings?  One way would be to shell out to 'virsh'
just to see if virsh fails to change the state (ie. a libvirt/C) or if
the problem is in the Java bindings.
Pausing/resuming Xen domains is a very common and well-tested
operation so I would be surprised if it's a libvirt problem, but you
never know ...
Rich.
-- 
Richard Jones, Emerging Technologies, Red Hat  
http://et.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/