> -----Original Message-----
> From: Lukas Straub <lukasstra...@web.de>
> Sent: Monday, September 16, 2019 3:20 AM
> To: qemu-devel <qemu-devel@nongnu.org>
> Cc: Zhang, Chen <chen.zh...@intel.com>; Jason Wang
> <jasow...@redhat.com>; Wen Congyang <wencongya...@huawei.com>;
> Xie Changlong <xiechanglon...@gmail.com>; kw...@redhat.com;
> mre...@redhat.com
> Subject: [PATCH v5 4/4] colo: Update Documentation for continuous
> replication
>
> Document the qemu command-line and qmp commands for continuous
> replication
>
> Signed-off-by: Lukas Straub <lukasstra...@web.de>
> ---
> docs/COLO-FT.txt | 212 +++++++++++++++++++++++++++----------
> docs/block-replication.txt | 28 +++--
> 2 files changed, 173 insertions(+), 67 deletions(-)
>
> diff --git a/docs/COLO-FT.txt b/docs/COLO-FT.txt index
> ad24680d13..e98c95ca2b 100644
> --- a/docs/COLO-FT.txt
> +++ b/docs/COLO-FT.txt
> @@ -145,35 +145,65 @@ The diagram just shows the main qmp command,
> you can get the detail in test procedure.
>
> == Test procedure ==
> -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
> -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
> -
> -2. On Secondary VM's QEMU monitor, issue command
> +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
> +
> +== Startup qemu ==
> +1. Primary:
> +# imagefolder="/mnt/vms/colo-test"
> +
> +The disks for the primary and secondary need to be the same before
> +starting colo # cp --reflink=auto $imagefolder/primary.qcow2
> +$imagefolder/primary-copy.qcow2
> +
> +# qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 512 -smp
> 1 -qmp stdio \
> + -vnc :0 -device piix3-usb-uhci -device usb-tablet -name primary \
> + -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 \
> + -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
> +
> +2. Secondary:
> +# imagefolder="/mnt/vms/colo-test"
> +
> +# qemu-img create -f qcow2 $imagefolder/secondary-active.qcow2 10G
> +
> +# qemu-img create -f qcow2 $imagefolder/secondary-hidden.qcow2 10G
> +
> +# qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 512 -smp
> 1 -qmp stdio \
> + -vnc :1 -device piix3-usb-uhci -device usb-tablet -name secondary \
> + -netdev tap,id=hn0,vhost=off,helper=/usr/lib/qemu/qemu-bridge-helper
> \
> + -device rtl8139,id=e0,netdev=hn0 \
> + -chardev socket,id=red0,host=127.0.0.1,port=9003,reconnect=1 \
> + -chardev socket,id=red1,host=127.0.0.1,port=9004,reconnect=1 \
> + -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 \
> + -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 \
> + -object filter-rewriter,id=rew0,netdev=hn0,queue=all \
> + -drive if=none,id=parent0,file.filename=$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 \
> + -drive
> +if=ide,id=colo-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,\
> +children.0=childs0 \
> + -incoming tcp:0:9998
> +
I know in your COLO test environment, all the node running in same physical
machine,
but current COLO start parameter demo easy to misunderstand users.
I think we can introduce primary node as 192.168.1.1, secondary node as
192.168.1.2.
Same issue for the VM image, we should avoid the "primary-copy.qow2".
Make two node independent is more clear.
> +
> +3. 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
> @@ -182,44 +212,112 @@ Note:
> same.
> c. It is better to put active disk and hidden disk in ramdisk.
>
> -3. On Primary VM's QEMU monitor, issue command:
> +4. 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.
> - b. xx.xx.xx.xx is the secondary physical machine's hostname or IP
> - c. The qmp command line must be run after running qmp command line in
> + b. The qmp command line must be run after running qmp command line in
> secondary qemu.
>
> -4. After the above steps, you will see, whenever you make changes to PVM,
> SVM will be synced.
> +5. 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
> +
> +6. Failover test
> +You can kill one of the VMs and Failover on the surviving VM:
> +
> +If you killed the Secondary, then follow "Primary Failover". After
> +that, if you want to resume the replication, follow "Primary resume
> replication"
> +
> +If you killed the Primary, then follow "Secondary Failover". After
> +that, if you want to resume the replication, follow "Secondary resume
> replication"
> +
> +== Primary Failover ==
> +The Secondary died, resume on the Primary
> +
> +{'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 (Steps 2 and 3 above), then:
Please note here the "then" is the original secondary node.
It is easy to misunderstand here.
> +{'execute': 'drive-mirror', 'arguments':{ 'device': 'colo-disk0',
> +'job-id': 'resync', 'target': 'nbd://127.0.0.1:9999/parent0', 'mode':
> +'existing', 'format': 'raw', 'sync': 'full'} }
> +
As I mentioned before, the 'nbd://127.0.0.1:9999/parent0' is very confusing,
user don't know which node will be connected.
> +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' } }
> +
The guest network have issues here in my test, I can't ping the guest from the
host.
Is it works in your test environment?
By the way, after finish this doc we can sync it to Qemu COLO WIKI page.
Thanks
Zhang Chen
> +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 (Steps 2 and 3 above, but with different image
> +than
> +primary-copy.qcow2 and different VNC port), 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'} }
> +
> +Wait until disk is synced, then:
> +{'execute': 'stop'}
> +{'execute': 'block-job-cancel', 'arguments':{ 'device': 'resync' } }
>
> -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.
> +{'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' } }
>
> -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
> +{'execute': 'object-add', 'arguments':{ 'qom-type': 'filter-mirror',
> +'id': 'm0', 'props': { 'insert': 'before', 'position': 'id=rew0',
> +'netdev': 'hn0', 'queue': 'tx', 'outdev': 'mirror0' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type':
> +'filter-redirector', 'id': 'redire0', 'props': { 'insert': 'before',
> +'position': 'id=rew0', 'netdev': 'hn0', 'queue': 'rx', 'indev':
> +'compare_out' } } }
> +{'execute': 'object-add', 'arguments':{ 'qom-type':
> +'filter-redirector', 'id': 'redire1', 'props': { 'insert': 'before',
> +'position': 'id=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' } } }
>
> -Secondary:
> - The primary host is down, so we should do the following thing:
> - { 'execute': 'nbd-server-stop' }
> +{'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.
> diff --git a/docs/block-replication.txt b/docs/block-replication.txt index
> 6bde6737fb..108e9166a8 100644
> --- a/docs/block-replication.txt
> +++ b/docs/block-replication.txt
> @@ -65,12 +65,12 @@ blocks that are already in QEMU.
> ^ || .----------
> | || | Secondary
> 1 Quorum || '----------
> - / \ ||
> - / \ ||
> - Primary 2 filter
> - disk ^
> virtio-blk
> - |
> ^
> - 3 NBD -------> 3 NBD
> |
> + / \ ||
> virtio-blk
> + / \ ||
> ^
> + Primary 2 filter
> |
> + disk ^
> 7 Quorum
> + |
> /
> + 3 NBD -------> 3 NBD
> /
> client || server
> 2 filter
> || ^
> ^
> --------. || |
> |
> @@ -106,6 +106,10 @@ any state that would otherwise be lost by the
> speculative write-through of the NBD server into the secondary disk. So
> before block replication, the primary disk and secondary disk should contain
> the same data.
>
> +7) The secondary also has a quorum node, so after secondary failover it
> +can become the new primary and continue replication.
> +
> +
> == Failure Handling ==
> There are 7 internal errors when block replication is running:
> 1. I/O error on primary disk
> @@ -171,16 +175,18 @@ Primary:
> leading whitespace.
> 5. The qmp command line must be run after running qmp command line in
> secondary qemu.
> - 6. After failover we need remove children.1 (replication driver).
> + 6. After primary failover we need remove children.1 (replication driver).
>
> Secondary:
> -drive if=none,driver=raw,file.filename=1.raw,id=colo1 \
> - -drive if=xxx,id=topxxx,driver=replication,mode=secondary,top-
> id=topxxx\
> + -drive
> + if=none,id=childs1,driver=replication,mode=secondary,top-id=childs1
> file.file.filename=active_disk.qcow2,\
> file.driver=qcow2,\
> file.backing.file.filename=hidden_disk.qcow2,\
> file.backing.driver=qcow2,\
> file.backing.backing=colo1
> + -drive if=xxx,driver=quorum,read-pattern=fifo,id=top-disk1,\
> + vote-threshold=1,children.0=childs1
>
> Then run qmp command in secondary qemu:
> { 'execute': 'nbd-server-start',
> @@ -234,6 +240,8 @@ Secondary:
> The primary host is down, so we should do the following thing:
> { 'execute': 'nbd-server-stop' }
>
> +Promote Secondary to Primary:
> + see COLO-FT.txt
> +
> TODO:
> -1. Continuous block replication
> -2. Shared disk
> +1. Shared disk
> --
> 2.20.1
