Re: [Qemu-devel] [Qemu-block] [PATCH COLO-Block v6 07/16] Add new block driver interface to connect/disconnect the remote target

[Wen Congyang]

On 07/02/2015 03:54 PM, Dr. David Alan Gilbert wrote:
> * Wen Congyang (address@hidden) wrote:
>> On 07/02/2015 02:42 AM, Dr. David Alan Gilbert wrote:
>>> * Wen Congyang (address@hidden) wrote:
>>>> On 07/01/2015 04:11 PM, Dr. David Alan Gilbert wrote:
>>>>> * Wen Congyang (address@hidden) wrote:
>>>>>> On 07/01/2015 03:01 AM, Dr. David Alan Gilbert wrote:
>>>>>>> * Wen Congyang (address@hidden) wrote:
>>>>>>>> On 06/27/2015 03:03 AM, Dr. David Alan Gilbert wrote:
>>>>>>>
>>>>>>> <snip>
>>>>>>>
>>>>>>>>> Ah, I hadn't realised you could do that; so do you just do:
>>>>>>>>>
>>>>>>>>> migrate_set_parameter colo on
>>>>>>>>> migrate -d -b tcp:otherhhost:port
>>>>>>>>>
>>>>>>>>> How does the secondary know to feed that data straight into the disk 
>>>>>>>>> without
>>>>>>>>> recording all the old data into the hidden-disk ?
>>>>>>>>
>>>>>>>> hidden disk and active disk will be made empty when starting block 
>>>>>>>> replication.
>>>>>>>
>>>>>>> Hmm, yes - I think I need to update to your current world; in the 
>>>>>>> version
>>>>>>> from the end of May, I get a 'error while loading state for instance 
>>>>>>> 0x0 of device 'block''
>>>>>>> if I try to use migrate -d -b 
>>>>>>> (the bdrv_write fails)
>>>>>>
>>>>>> Can you give me both primary and secondary qemu's command? I think the 
>>>>>> command line is wrong,
>>>>>> and disk migration fails.
>>>>>>
>>>>>
>>>>> Primary:
>>>>>
>>>>> ./try/bin/qemu-system-x86_64 -enable-kvm -nographic \
>>>>>      -boot c -m 4096 -smp 4 -S \
>>>>>      -name debug-threads=on -trace events=trace-file \
>>>>>      -netdev tap,id=hn0,script=$PWD/ifup-prim,\
>>>>> downscript=no,colo_script=$PWD/qemu/scripts/colo-proxy-script.sh,colo_nicname=em4
>>>>>  \
>>>>>      -device e1000,mac=9c:da:4d:1c:b5:89,id=net-pci0,netdev=hn0 \
>>>>>      -drive if=virtio,driver=quorum,read-pattern=fifo,no-connect=on,\
>>>>> cache=none,aio=native,\
>>>>> children.0.file.filename=./bugzilla.raw,\
>>>>> children.0.driver=raw,\
>>>>> children.1.file.driver=nbd,\
>>>>> children.1.file.host=ibpair,\
>>>>> children.1.file.port=8889,\
>>>>> children.1.file.export=colo1,\
>>>>> children.1.driver=replication,\
>>>>> children.1.mode=primary,\
>>>>> children.1.ignore-errors=on
>>>>
>>>> Add id=nbd_target1 to primary disk option, and try it. Disk migration 
>>>> needs the same id to sync
>>>> the disk.
>>>
>>> Thank you! That worked nicely.
>>> The only odd thing was that the hidden disk on the secondary went upto ~2GB 
>>> in size during
>>> the disk copy; (This is still on the version you posted at the end of may).
>>> I don't really understand why it was 2GB - the disk was 40GB, and qemu-img 
>>> tells me that
>>> 2.6GB of it were used.   Still, it would be good to avoid the overhead of 
>>> going through
>>> the hidden disk on the secondary for the initial replication.
>>
>> Yes, I have fixed it in v7: starting backup job later.
> 
> Thanks, I'll try it.

Note: the usage is changed, and you can get the usage from the wiki:
http://wiki.qemu.org/Features/COLO

Thanks
Wen Congyang

> 
> Dave
> 
>>
>> Thanks
>> Wen Congyang
>>
>>>
>>> Dave
>>>
>>>> Thanks
>>>> Wen Congyang
>>>>
>>>>>
>>>>>
>>>>> Secondary:
>>>>>
>>>>> ./try/bin/qemu-system-x86_64 -enable-kvm -nographic \
>>>>>      -boot c -m 4096 -smp 4 -S \
>>>>>      -name debug-threads=on -trace events=trace-file \
>>>>>      -netdev tap,id=hn0,script=$PWD/ifup-slave,\
>>>>> downscript=no,colo_script=$PWD/qemu/scripts/colo-proxy-script.sh,colo_nicname=em4
>>>>>  \
>>>>>      -device e1000,mac=9c:da:4d:1c:b5:89,id=net-pci0,netdev=hn0 \
>>>>>      -drive 
>>>>> if=none,driver=raw,file=bugzilla.raw,id=nbd_target1,cache=none,aio=native 
>>>>> \
>>>>>      -drive 
>>>>> if=virtio,driver=replication,mode=secondary,export=colo1,throttling.bps-total-max=70000000,\
>>>>> file.file.filename=/run/colo-active-disk.qcow2,\
>>>>> file.driver=qcow2,\
>>>>> file.backing_reference.drive_id=nbd_target1,\
>>>>> file.backing_reference.hidden-disk.file.filename=/run/colo-hidden-disk.qcow2,\
>>>>> file.backing_reference.hidden-disk.driver=qcow2,\
>>>>> file.backing_reference.hidden-disk.allow-write-backing-file=on \
>>>>>      -incoming tcp:0:8888
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Dave
>>>>>
>>>>>>>>>> If the user uses mirror job, we don't cancel the mirror job now.
>>>>>>>>>
>>>>>>>>> It would be good to get it to work with mirror, that seems preferred 
>>>>>>>>> these
>>>>>>>>> days to the old block migration.
>>>>>>>>
>>>>>>>> In normal migration, is mirror job created and cancelled by libvirt?
>>>>>>>
>>>>>>> Yes, I think so; you should be able to turn on full logging on libvirt 
>>>>>>> and
>>>>>>> watch the qmp commands it sends.
>>>>>>
>>>>>> Supporting mirror job in my TODO list now. But I think we should focus 
>>>>>> the basci function now.
>>>>>>
>>>>>> Thanks
>>>>>> Wen Congyang
>>>>>>
>>>>>>>
>>>>>>> Dave
>>>>>>>
>>>>>>> --
>>>>>>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>>>>>>> .
>>>>>>>
>>>>>>
>>>>> --
>>>>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>>>>> .
>>>>>
>>>>
>>> --
>>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>>> .
>>>
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
> .
>