Re: [Qemu-devel] [PATCH v2 3/3] Update Documentation

[Zhang, Chen]

Hi Lukas,

Please address Markus's comments change this patch's name in next version.
And I wrote some comments behind, please check it.
Firstly, Please remove all the trailing whitespace in this patch.


> -----Original Message-----
> From: Lukas Straub <address@hidden>
> Sent: Friday, August 16, 2019 2:49 AM
> To: qemu-devel <address@hidden>
> Cc: Zhang, Chen <address@hidden>; Jason Wang
> <address@hidden>; Wen Congyang <address@hidden>;
> Xie Changlong <address@hidden>
> Subject: [PATCH v2 3/3] Update Documentation
> 
> Document the qemu command-line and qmp commands for continious
> replication
> 
> Signed-off-by: Lukas Straub <address@hidden>
> ---
>  docs/COLO-FT.txt | 185 +++++++++++++++++++++++++++++++++++--------
> ----
>  1 file changed, 138 insertions(+), 47 deletions(-)
> 
> diff --git a/docs/COLO-FT.txt b/docs/COLO-FT.txt index
> ad24680d13..c08bfbd3a8 100644
> --- a/docs/COLO-FT.txt
> +++ b/docs/COLO-FT.txt
> @@ -145,35 +145,64 @@ The diagram just shows the main qmp command,
> you can get the detail  in test procedure.
> 
>  == Test procedure ==
> +Note: Here we are running both instances on the same Machine for
> +testing, change the IP Addresses if you want to run it on two Hosts
> +
>  1. Startup qemu
>  Primary:
> -# qemu-system-x86_64 -accel kvm -m 2048 -smp 2 -qmp stdio -name
> primary \
> -  -device piix3-usb-uhci -vnc :7 \
> -  -device usb-tablet -netdev tap,id=hn0,vhost=off \
> -  -device virtio-net-pci,id=net-pci0,netdev=hn0 \
> -  -drive if=virtio,id=primary-disk0,driver=quorum,read-pattern=fifo,vote-
> threshold=1,\
> -         children.0.file.filename=1.raw,\
> -         children.0.driver=raw -S
> +# imagefolder="/mnt/vms/colo-test"
> +
> +# cp --reflink=auto $imagefolder/primary.qcow2
> +$imagefolder/primary-copy.qcow2

I think you can tell other people here that we need two same disk image before 
COLO startup.
The name "primary and primary-copy" will make reader very confused.

> +
> +# qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 512 -smp
> 1 -qmp stdio \
> +   -vnc :0 -k de -device piix3-usb-uhci -device usb-tablet -name primary \

What's mean of the "-k de" ?

> +   -netdev tap,id=hn0,vhost=off,helper=/usr/lib/qemu/qemu-bridge-helper
> \
> +   -device rtl8139,id=e0,netdev=hn0 \
> +   -chardev socket,id=mirror0,host=127.0.0.1,port=9003,server,nowait \
> +   -chardev socket,id=compare1,host=127.0.0.1,port=9004,server,wait \
> +   -chardev socket,id=compare0,host=127.0.0.1,port=9001,server,nowait \
> +   -chardev socket,id=compare0-0,host=127.0.0.1,port=9001 \
> +   -chardev socket,id=compare_out,host=127.0.0.1,port=9005,server,nowait
> \
> +   -chardev socket,id=compare_out0,host=127.0.0.1,port=9005 \
> +   -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 \
> +   -object filter-
> redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out \
> +   -object filter-
> redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 \
> +   -object iothread,id=iothread1 \
> +   -object
> +colo-compare,id=comp0,primary_in=compare0-
> 0,secondary_in=compare1,\
> +outdev=compare_out0,iothread=iothread1 \

Please keep the space style.

> +   -drive
> +if=ide,id=colo-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,\
> +children.0.file.filename=$imagefolder/primary.qcow2,children.0.driver=q
> +cow2 -S
> +
>  Secondary:
> -# qemu-system-x86_64 -accel kvm -m 2048 -smp 2 -qmp stdio -name
> secondary \
> -  -device piix3-usb-uhci -vnc :7 \
> -  -device usb-tablet -netdev tap,id=hn0,vhost=off \
> -  -device virtio-net-pci,id=net-pci0,netdev=hn0 \
> -  -drive if=none,id=secondary-disk0,file.filename=1.raw,driver=raw,node-
> name=node0 \
> -  -drive if=virtio,id=active-disk0,driver=replication,mode=secondary,\
> -         file.driver=qcow2,top-id=active-disk0,\
> -         file.file.filename=/mnt/ramfs/active_disk.img,\
> -         file.backing.driver=qcow2,\
> -         file.backing.file.filename=/mnt/ramfs/hidden_disk.img,\
> -         file.backing.backing=secondary-disk0 \
> -  -incoming tcp:0:8888
> +# imagefolder="/mnt/vms/colo-test"
> +
> +# qemu-img create -f qcow2 $imagefolder/secondary-active.qcow2 10G
> +
> +# qemu-img create -f qcow2 $imagefolder/secondary-hidden.qcow2 10G
> +
> +# qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 512 -smp
> 1 -qmp stdio \
> +   -vnc :1 -k de -device piix3-usb-uhci -device usb-tablet -name secondary \
> +   -netdev tap,id=hn0,vhost=off,helper=/usr/lib/qemu/qemu-bridge-helper
> \
> +   -device rtl8139,id=e0,netdev=hn0 \
> +   -chardev socket,id=red0,host=127.0.0.1,port=9003,reconnect=1 \
> +   -chardev socket,id=red1,host=127.0.0.1,port=9004,reconnect=1 \
> +   -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 \
> +   -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 \
> +   -object filter-rewriter,id=rew0,netdev=hn0,queue=all \
> +   -drive if=none,id=parent0,file.filename=$imagefolder/primary-
> copy.qcow2,driver=qcow2 \
> +   -drive
> +if=none,id=childs0,driver=replication,mode=secondary,file.driver=qcow2,
> +\
> +top-id=childs0,file.file.filename=$imagefolder/secondary-active.qcow2,\
> +file.backing.driver=qcow2,file.backing.file.filename=$imagefolder/secon
> +dary-hidden.qcow2,\
> +file.backing.backing=parent0 \

Please keep the space style.

> +   -drive
> +if=ide,id=colo-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,\
> +children.0.file=childs0,children.0.driver=raw \
> +   -incoming tcp:0:9998
> +

Here, you changed the original block design, can you explain the reasons why we 
need to do this?
Please draw a ASCII diagram to describe COLO block detail.

> 
>  2. On Secondary VM's QEMU monitor, issue command
> {'execute':'qmp_capabilities'} -{ 'execute': 'nbd-server-start',
> -  'arguments': {'addr': {'type': 'inet', 'data': {'host': 'xx.xx.xx.xx', 
> 'port':
> '8889'} } } -}
> -{'execute': 'nbd-server-add', 'arguments': {'device': 'secondary-disk0',
> 'writable': true } }
> +{'execute': 'nbd-server-start', 'arguments': {'addr': {'type': 'inet',
> +'data': {'host': '127.0.0.1', 'port': '9999'} } } }
> +{'execute': 'nbd-server-add', 'arguments': {'device': 'parent0',
> +'writable': true } }
> 
>  Note:
>    a. The qmp command nbd-server-start and nbd-server-add must be run
> @@ -184,12 +213,10 @@ Note:
> 
>  3. On Primary VM's QEMU monitor, issue command:
>  {'execute':'qmp_capabilities'}
> -{ 'execute': 'human-monitor-command',
> -  'arguments': {'command-line': 'drive_add -n buddy
> driver=replication,mode=primary,file.driver=nbd,file.host=xx.xx.xx.xx,file.p
> ort=8889,file.export=secondary-disk0,node-name=nbd_client0'}}
> -{ 'execute':'x-blockdev-change', 'arguments':{'parent': 'primary-disk0',
> 'node': 'nbd_client0' } } -{ 'execute': 'migrate-set-capabilities',
> -      'arguments': {'capabilities': [ {'capability': 'x-colo', 'state': true 
> } ] } }
> -{ 'execute': 'migrate', 'arguments': {'uri': 'tcp:xx.xx.xx.xx:8888' } }
> +{'execute': 'human-monitor-command', 'arguments': {'command-line':
> +'drive_add -n buddy
> +driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.1,fil
> +e.port=9999,file.export=parent0,node-name=replication0'}}
> +{'execute': 'x-blockdev-change', 'arguments':{'parent': 'colo-disk0',
> +'node': 'replication0' } }
> +{'execute': 'migrate-set-capabilities', 'arguments': {'capabilities': [
> +{'capability': 'x-colo', 'state': true } ] } }
> +{'execute': 'migrate', 'arguments': {'uri': 'tcp:127.0.0.1:9998' } }
> 
>    Note:
>    a. There should be only one NBD Client for each primary disk.
> @@ -199,27 +226,91 @@ Note:
> 
>  4. After the above steps, you will see, whenever you make changes to PVM,
> SVM will be synced.
>  You can issue command '{ "execute": "migrate-set-parameters" ,
> "arguments":{ "x-checkpoint-delay": 2000 } }'
> -to change the checkpoint period time
> +to change the idle checkpoint period time
> 
>  5. Failover test
> -You can kill Primary VM and run 'x_colo_lost_heartbeat' in Secondary VM's -
> monitor at the same time, then SVM will failover and client will not detect
> this -change.
> +You can kill one of the VMs and Failover on the surviving VM:
> 
> -Before issuing '{ "execute": "x-colo-lost-heartbeat" }' command, we have to
> -issue block related command to stop block replication.
> -Primary:
> -  Remove the nbd child from the quorum:
> -  { 'execute': 'x-blockdev-change', 'arguments': {'parent': 'colo-disk0', 
> 'child':
> 'children.1'}}
> -  { 'execute': 'human-monitor-command','arguments': {'command-line':
> 'drive_del blk-buddy0'}}
> -  Note: there is no qmp command to remove the blockdev now
> +== Primary Failover ==
> +The Secondary died, resume on the Primary
> 
> -Secondary:
> -  The primary host is down, so we should do the following thing:
> -  { 'execute': 'nbd-server-stop' }
> +{'execute': 'x-blockdev-change', 'arguments':{ 'parent': 'colo-disk0',
> +'child': 'children.1'} }
> +{'execute': 'human-monitor-command', 'arguments':{ 'command-line':
> +'drive_del replication0' } }
> +{'execute': 'object-del', 'arguments':{ 'id': 'comp0' } }
> +{'execute': 'object-del', 'arguments':{ 'id': 'iothread1' } }
> +{'execute': 'object-del', 'arguments':{ 'id': 'm0' } }
> +{'execute': 'object-del', 'arguments':{ 'id': 'redire0' } }
> +{'execute': 'object-del', 'arguments':{ 'id': 'redire1' } }
> +{'execute': 'x-colo-lost-heartbeat' }
> +
> +== Secondary Failover ==
> +The Primary died, resume on the Secondary and prepare to become the
> new
> +Primary
> +
> +{'execute': 'nbd-server-stop'}
> +{'execute': 'x-colo-lost-heartbeat'}
> +
> +{'execute': 'object-del', 'arguments':{ 'id': 'f2' } }
> +{'execute': 'object-del', 'arguments':{ 'id': 'f1' } }
> +{'execute': 'chardev-remove', 'arguments':{ 'id': 'red1' } }
> +{'execute': 'chardev-remove', 'arguments':{ 'id': 'red0' } }
> +
> +{'execute': 'chardev-add', 'arguments':{ 'id': 'mirror0', 'backend':
> +{'type': 'socket', 'data': {'addr': { 'type': 'inet', 'data': { 'host':
> +'127.0.0.1', 'port': '9003' } }, 'server': true } } } }
> +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare1', 'backend':
> +{'type': 'socket', 'data': {'addr': { 'type': 'inet', 'data': { 'host':
> +'127.0.0.1', 'port': '9004' } }, 'server': true } } } }
> +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare0', 'backend':
> +{'type': 'socket', 'data': {'addr': { 'type': 'inet', 'data': { 'host':
> +'127.0.0.1', 'port': '9001' } }, 'server': true } } } }
> +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare0-0', 'backend':
> +{'type': 'socket', 'data': {'addr': { 'type': 'inet', 'data': { 'host':
> +'127.0.0.1', 'port': '9001' } }, 'server': false } } } }
> +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare_out',
> +'backend': {'type': 'socket', 'data': {'addr': { 'type': 'inet',
> +'data': { 'host': '127.0.0.1', 'port': '9005' } }, 'server': true } } }
> +}
> +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare_out0',
> +'backend': {'type': 'socket', 'data': {'addr': { 'type': 'inet',
> +'data': { 'host': '127.0.0.1', 'port': '9005' } }, 'server': false } }
> +} }
> +
> +== Primary resume replication ==
> +Resume replication after new Secondary is up.
> +
> +Start the new Secondary, then:
> +{'execute': 'drive-mirror', 'arguments':{ 'device': 'colo-disk0',
> +'job-id': 'resync', 'target': 'nbd://127.0.0.1:9999/parent0', 'mode':
> +'existing', 'format': 'raw', 'sync': 'full'} }

I think the original secondary node has stopped the nbd server in failover:
> +{'execute': 'nbd-server-stop'}
> +{'execute': 'x-colo-lost-heartbeat'}

Why you can connect to it?

And please add new Secondary node start up script here,
I think it is different with original secondary node script.
same issue in resume secondary.

> +
> +Wait until disk is synced, then:
> +{'execute': 'stop'}
> +{'execute': 'block-job-cancel', 'arguments':{ 'device': 'resync'} }
> +
> +{'execute': 'human-monitor-command', 'arguments':{ 'command-line':
> +'drive_add -n buddy
> +driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.1,fil
> +e.port=9999,file.export=parent0,node-name=replication0'}}
> +{'execute': 'x-blockdev-change', 'arguments':{ 'parent': 'colo-disk0',
> +'node': 'replication0' } }
> +
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'filter-mirror',
> +'id': 'm0', 'props': { 'netdev': 'hn0', 'queue': 'tx', 'outdev':
> +'mirror0' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type':
> +'filter-redirector', 'id': 'redire0', 'props': { 'netdev': 'hn0',
> +'queue': 'rx', 'indev': 'compare_out' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type':
> +'filter-redirector', 'id': 'redire1', 'props': { 'netdev': 'hn0',
> +'queue': 'rx', 'outdev': 'compare0' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'iothread', 'id':
> +'iothread1' } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'colo-compare',
> +'id': 'comp0', 'props': { 'primary_in': 'compare0-0', 'secondary_in':
> +'compare1', 'outdev': 'compare_out0', 'iothread': 'iothread1' } } }
> +
> +{'execute': 'migrate-set-capabilities', 'arguments':{ 'capabilities': [
> +{'capability': 'x-colo', 'state': true } ] } }
> +{'execute': 'migrate', 'arguments':{ 'uri': 'tcp:127.0.0.1:9998' } }
> +
> +Note:
> +If this Primary previously was a Secondary, then we need to insert the
> +filters before the filter-rewriter by using the
> +"'insert': 'before', 'position': 'rew0'" Options. See below.
> +
> +== Secondary resume replication ==
> +Become Primary and resume replication after new Secondary is up.
> +
> +Start the new Secondary, then:
> +{'execute': 'drive-mirror', 'arguments':{ 'device': 'colo-disk0',
> +'job-id': 'resync', 'target': 'nbd://127.0.0.1:9999/parent0', 'mode':
> +'existing', 'format': 'raw', 'sync': 'full'} }

Same issue as primary resume.

I want to re-tested the resume function but got stuck here.

Thanks
Zhang Chen

> +
> +Wait until disk is synced, then:
> +{'execute': 'stop'}
> +{'execute': 'block-job-cancel', 'arguments':{ 'device': 'resync' } }
> +
> +{'execute': 'human-monitor-command', 'arguments':{ 'command-line':
> +'drive_add -n buddy
> +driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.1,fil
> +e.port=9999,file.export=parent0,node-name=replication0'}}
> +{'execute': 'x-blockdev-change', 'arguments':{ 'parent': 'colo-disk0',
> +'node': 'replication0' } }
> +
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'filter-mirror',
> +'id': 'm0', 'props': { 'insert': 'before', 'position': 'rew0',
> +'netdev': 'hn0', 'queue': 'tx', 'outdev': 'mirror0' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type':
> +'filter-redirector', 'id': 'redire0', 'props': { 'insert': 'before',
> +'position': 'rew0', 'netdev': 'hn0', 'queue': 'rx', 'indev':
> +'compare_out' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type':
> +'filter-redirector', 'id': 'redire1', 'props': { 'insert': 'before',
> +'position': 'rew0', 'netdev': 'hn0', 'queue': 'rx', 'outdev':
> +'compare0' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'iothread', 'id':
> +'iothread1' } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'colo-compare',
> +'id': 'comp0', 'props': { 'primary_in': 'compare0-0', 'secondary_in':
> +'compare1', 'outdev': 'compare_out0', 'iothread': 'iothread1' } } }
> +
> +{'execute': 'migrate-set-capabilities', 'arguments':{ 'capabilities': [
> +{'capability': 'x-colo', 'state': true } ] } }
> +{'execute': 'migrate', 'arguments':{ 'uri': 'tcp:127.0.0.1:9998' } }
> 
>  == TODO ==
> -1. Support continuous VM replication.
> -2. Support shared storage.
> -3. Develop the heartbeat part.
> -4. Reduce checkpoint VM’s downtime while doing checkpoint.
> +1. Support shared storage.
> +2. Develop the heartbeat part.
> +3. Reduce checkpoint VM’s downtime while doing checkpoint.
> --
> 2.20.1