6:28 a.m.
Hi,
These are my doubts:
1. I tried live migration of Ubuntu 11.04 from the one physical machine to
another using the migrate() function. I connected via tcp in the destination
URI and migrated successfully(lesser than 2 seconds). I tried running virsh
list --all on the destination PM and confirmed that the VM had been migrated
successfully.
When I tried checking ps aux | grep vmname where vmname was the name of the
VM migrated, I could see that on the source PM the thread was still active
with the PID though the machine had been migrated successfully.
Shouldn't the vmname not be listed at all on the source PM's side,if it has
been completely migrated?
Isn't 2 seconds too little(considering the memory allotted to the VM was
128MB and I'm using a 100Mbps LAN switch, time taken=size/speed~10 seconds).
Why is virsh list --all showing me that the VM migrated to be shutdown on
the source PM? If it's been completely migrated, shouldn't the entry be
removed completely?
2. Is there any way to set the CPU limit in terms of % of CPU used on a VCPU
using libvirt function? As in, if I want my VM to use just 10% of VCPU 1.
3. I'm developing an application in Java to monitor VM usage(Memory,CPU,
Network etc). Are there any easily integrable graph plotting applications I
could integrate with?
Thanks for your time.
Regards,
Preethi
11:08 a.m.
On 10/07/2011 05:28 AM, PREETHI RAMESH wrote:
Hi,
These are my doubts:
I'll answer what I can, but you'll have to hope that others chime in as
well.
1. I tried live migration of Ubuntu 11.04 from the one physical machine to
another using the migrate() function. I connected via tcp in the destination
URI and migrated successfully(lesser than 2 seconds). I tried running virsh
list --all on the destination PM and confirmed that the VM had been migrated
successfully.
When I tried checking ps aux | grep vmname where vmname was the name of the
VM migrated, I could see that on the source PM the thread was still active
with the PID though the machine had been migrated successfully.
That's odd - either the migration was still going on at the time of your
ps, or something else went wrong. What version of libvirt are you using
on source and destination? Migration should not complete until the qemu
process on the source has gone away. Are you sure you were interpreting
the ps listing correctly?
Shouldn't the vmname not be listed at all on the source PM's side,if it has
been completely migrated?
Isn't 2 seconds too little(considering the memory allotted to the VM was
128MB and I'm using a 100Mbps LAN switch, time taken=size/speed~10 seconds).
Not necessarily. Migration can go faster than the memory size if the
source can prove that some of the memory is untouched, and can therefore
convey that information to the destination without copying entire blocks
of 0 over the line. That is, qemu can do some forms of compression to
speed up migration.
Why is virsh list --all showing me that the VM migrated to be shutdown on
the source PM? If it's been completely migrated, shouldn't the entry be
removed completely?
You probably didn't specify 'virsh migrate --persistent
--undefinesource' - the --persistent flag says to keep the guest
definition persistent on the definition, and the --undefinesource says
to remove the guest definition on the source (all on successful
migration, of course). Without --persistent, the guest is transient;
and without --undefinesource, 'virsh list --all' will still list the
guest configuration on the source (and it is up to you to only run the
guest on one of the two machines at a given time, although recent
improvements in sanlock or fcntl lock managers can help prevent
accidental running of the same guest from two machines).
2. Is there any way to set the CPU limit in terms of % of CPU used on a VCPU
using libvirt function? As in, if I want my VM to use just 10% of VCPU 1.
To limit a guests' use of a VCPU, you have to do that within the guest.
You probably meant to ask whether you can constrain a guest using 100%
of its VCPU to only consume 10% of the physical CPU on the host that is
providing the VCPU to the guest. And yes, with recent additions to the
xml regarding cpu tuning, you can do something like that:
http://libvirt.org/formatdomain.html#elementsCPUTuning
3. I'm developing an application in Java to monitor VM usage(Memory,CPU,
Network etc). Are there any easily integrable graph plotting applications I
could integrate with?
Sorry, I can't answer this one.
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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PREETHI RAMESH