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s=dbaedf251592; t=1570280741; bh=eRknjklDO4NY1lsxHvB+cdjugcevyUUzS5Qo8fAz594=; h=X-UI-Sender-Class:Date:From:To:Cc:Subject:In-Reply-To:References; b=kUO43oqfertyRVoX3BHKfgSFWnU9yEMdS0lP4sy3Qe32RAPINvWDlk5qNZXUAb6QO MB7xQitoVJKVdRJKFahCCiDsnqXtZV2LI+XN9VMtSHXGxRAtH0TwUrNde1AfOm+4j5 XJ3AsrALNGk0DsPkRkrL40lsipO5nluPfQfoOtSk= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from luklap ([87.123.206.231]) by smtp.web.de (mrweb102 [213.165.67.124]) with ESMTPSA (Nemesis) id 0MBTEQ-1iRDbH1Mv8-00ARyr; Sat, 05 Oct 2019 15:05:41 +0200 Date: Sat, 5 Oct 2019 15:05:40 +0200 From: Lukas Straub To: qemu-devel Subject: [PATCH v6 4/4] colo: Update Documentation for continuous replication Message-ID: <23a8a3d00523999e2b6f52074fa0f4c7f3f469ef.1570280098.git.lukasstraub2@web.de> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:ELni6//FQTpoTrgUs0yyob4vpjF/H8Ymoca3aZLNyFHlqvh3GqZ g3mIoANPHXLmRGVpVvEm5e9yCe11yzPB2fLLARwduyin0V5A90z0ApOgvOEnYKG9sIJPDWn pwsjbAwAmNsV8pEEYlSG+2FPJkxMPUr7sYL8B5+IRo87WdNQTuCH+76dPNnVXAiesBaKqUy rvhh+n0/nKlMuX9A0Cq0Q== X-UI-Out-Filterresults: notjunk:1;V03:K0:69SM3qQhG1M=:DvHJngTg+PnCrZMaFozd7J y/brXX17fogZrIgx/r9ZmOvngmzHsC98b9X9+zneMDk534SWXOuSyDIFetcxiiA2vl4XDXzNZ oiKRj9lxxk0I5UT6sjvAXMh2CoZR/s6PTyIQpB9P+3Sqr4j6/opITEbBC/rMQ2XNHxSEXRXZs RdJsV3E4IYMb/F50KJRMyrkQAfJQ1iEs2WSTC8iKzHocy5apyJZh7xeGW7SEruDbrujjdQuOM 4IRfbw6GL0attcWH7MbCvzLu9oKt8OO3C4ufeAj7eVM22nzev8zaZg57pautRst8p2tSEhzIe /086jfs776egn1IrdVaaB5L0ijEzMfDeFztp1lyzZLd3MiN/Sis7Pt8RCi9p9hW7Cpdn9QXYR JyhnCISct77Moq9ZpzUl1FujnMFYdb/9jjVr5Q3rIwtUsHPtUFxyuzlvfQbayuvwn6xVwXd6K UpcJwXlreATS+o8aI/hWBuUHOWI/ch015g/TByju5aLXTPtpy+T7C8rdoM2mvKWy+AMhSEtBp 2437khHUexbKaHe0LjEKuEtKlvqpIp0SpreKD8THLFCLPeiByj4XU9d9iB4X8mFWYkBe7U283 BcxOFFPagSRWCmJb68AhPprf1TvYB4gPoR3OhWli8fVgBOO463/G5lxYf2Ms3k3olpR+iVXCk SuYIkn77frwr2tCC5LC1zHHteMJjlt2ZTg9uBMmjwZBQ+TXzJw83GKGdQTYSYcu6T1Nj5J0CY sYpdR0qfBMSweqDUlZMHisWHQrENfhLisjaLr+dVYr/AGQH5YcNlLaoFrj1tMh5fuR4jpBGfN +MHq/DUDkJNz9AU01yL4DmG/6/whuhsiWlLjhdMVQagIiwx9w1c3Jir20ljgqZlVvBrSUiBij CL5KJPhl6f90AVC64UojcWMcqRoa/cB0L0oe1iZx7jFFleLP2EEwrwr8whaVA6J9zkLkajK1f +wnWB1v5Yeq2Lm7nEzibna24fRsbzm4Zy4POh2AaIaBWdU9vvaVjgJ3m8dkzmsnZ5S0317A3E EkfvTBLJo3FIo5KFWPeYAbKswT06ufbskRAw9hXGI4brSLUkcuvOeZYENGi1wzUmboNdox2Zw YKKzvsEA4kTB1TIfpMds+kv+Xr0WqqkN956CUN4mYbf+9s3DKfUUWYCOKenpQhPhhO1kWiGHd lhCBBOpCBiOM1aUGB3Gps/HVA1X63GC6S4v1lrrpLFBi+mKHHEqt57+VqBEcuKYUHQky9n/qI YCXi/PXmGSBcnbPmppTh/gTb4fuKXCivs/yXRGBBULErrz3hsKy3xWbh7+ls= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 212.227.17.12 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , qemu-block , Wen Congyang , Jason Wang , Max Reitz , Zhang Chen , Xie Changlong Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Document the qemu command-line and qmp commands for continuous replication Signed-off-by: Lukas Straub --- docs/COLO-FT.txt | 213 +++++++++++++++++++++++++++---------- docs/block-replication.txt | 28 +++-- 2 files changed, 174 insertions(+), 67 deletions(-) diff --git a/docs/COLO-FT.txt b/docs/COLO-FT.txt index ad24680d13..bc1a0ccb99 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. =20 =3D=3D Test procedure =3D=3D -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=3Dhn0,vhost=3Doff \ - -device virtio-net-pci,id=3Dnet-pci0,netdev=3Dhn0 \ - -drive if=3Dvirtio,id=3Dprimary-disk0,driver=3Dquorum,read-pattern=3Dfif= o,vote-threshold=3D1,\ - children.0.file.filename=3D1.raw,\ - children.0.driver=3Draw -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=3Dhn0,vhost=3Doff \ - -device virtio-net-pci,id=3Dnet-pci0,netdev=3Dhn0 \ - -drive if=3Dnone,id=3Dsecondary-disk0,file.filename=3D1.raw,driver=3Draw= ,node-name=3Dnode0 \ - -drive if=3Dvirtio,id=3Dactive-disk0,driver=3Dreplication,mode=3Dseconda= ry,\ - file.driver=3Dqcow2,top-id=3Dactive-disk0,\ - file.file.filename=3D/mnt/ramfs/active_disk.img,\ - file.backing.driver=3Dqcow2,\ - file.backing.file.filename=3D/mnt/ramfs/hidden_disk.img,\ - file.backing.backing=3Dsecondary-disk0 \ - -incoming tcp:0:8888 - -2. On Secondary VM's QEMU monitor, issue command +Note: Here we are running both instances on the same Host for testing, +change the IP Addresses if you want to run it on two Hosts. Initally +127.0.0.1 is the Primary Host and 127.0.0.2 is the Secondary Host. + +=3D=3D Startup qemu =3D=3D +1. Primary: +Note: Initally, $imagefolder/primary.qcow2 needs to be copied to all Hosts. +# imagefolder=3D"/mnt/vms/colo-test-primary" + +# qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 512 -smp 1 -qmp = stdio \ + -device piix3-usb-uhci -device usb-tablet -name primary \ + -netdev tap,id=3Dhn0,vhost=3Doff,helper=3D/usr/lib/qemu/qemu-bridge-hel= per \ + -device rtl8139,id=3De0,netdev=3Dhn0 \ + -chardev socket,id=3Dmirror0,host=3D0.0.0.0,port=3D9003,server,nowait \ + -chardev socket,id=3Dcompare1,host=3D0.0.0.0,port=3D9004,server,wait \ + -chardev socket,id=3Dcompare0,host=3D127.0.0.1,port=3D9001,server,nowai= t \ + -chardev socket,id=3Dcompare0-0,host=3D127.0.0.1,port=3D9001 \ + -chardev socket,id=3Dcompare_out,host=3D127.0.0.1,port=3D9005,server,no= wait \ + -chardev socket,id=3Dcompare_out0,host=3D127.0.0.1,port=3D9005 \ + -object filter-mirror,id=3Dm0,netdev=3Dhn0,queue=3Dtx,outdev=3Dmirror0 \ + -object filter-redirector,netdev=3Dhn0,id=3Dredire0,queue=3Drx,indev=3D= compare_out \ + -object filter-redirector,netdev=3Dhn0,id=3Dredire1,queue=3Drx,outdev= =3Dcompare0 \ + -object iothread,id=3Diothread1 \ + -object colo-compare,id=3Dcomp0,primary_in=3Dcompare0-0,secondary_in=3D= compare1,\ +outdev=3Dcompare_out0,iothread=3Diothread1 \ + -drive if=3Dide,id=3Dcolo-disk0,driver=3Dquorum,read-pattern=3Dfifo,vot= e-threshold=3D1,\ +children.0.file.filename=3D$imagefolder/primary.qcow2,children.0.driver=3D= qcow2 -S + +2. Secondary: +# imagefolder=3D"/mnt/vms/colo-test-secondary" +# primary_ip=3D127.0.0.1 + +# qemu-img create -f qcow2 $imagefolder/secondary-active.qcow2 10G + +# qemu-img create -f qcow2 $imagefolder/secondary-hidden.qcow2 10G + +# qemu-system-x86_64 -enable-kvm -cpu qemu64,+kvmclock -m 512 -smp 1 -qmp = stdio \ + -device piix3-usb-uhci -device usb-tablet -name secondary \ + -netdev tap,id=3Dhn0,vhost=3Doff,helper=3D/usr/lib/qemu/qemu-bridge-hel= per \ + -device rtl8139,id=3De0,netdev=3Dhn0 \ + -chardev socket,id=3Dred0,host=3D$primary_ip,port=3D9003,reconnect=3D1 \ + -chardev socket,id=3Dred1,host=3D$primary_ip,port=3D9004,reconnect=3D1 \ + -object filter-redirector,id=3Df1,netdev=3Dhn0,queue=3Dtx,indev=3Dred0 \ + -object filter-redirector,id=3Df2,netdev=3Dhn0,queue=3Drx,outdev=3Dred1= \ + -object filter-rewriter,id=3Drew0,netdev=3Dhn0,queue=3Dall \ + -drive if=3Dnone,id=3Dparent0,file.filename=3D$imagefolder/primary.qcow= 2,driver=3Dqcow2 \ + -drive if=3Dnone,id=3Dchilds0,driver=3Dreplication,mode=3Dsecondary,fil= e.driver=3Dqcow2,\ +top-id=3Dchilds0,file.file.filename=3D$imagefolder/secondary-active.qcow2,\ +file.backing.driver=3Dqcow2,file.backing.file.filename=3D$imagefolder/seco= ndary-hidden.qcow2,\ +file.backing.backing=3Dparent0 \ + -drive if=3Dide,id=3Dcolo-disk0,driver=3Dquorum,read-pattern=3Dfifo,vot= e-threshold=3D1,\ +children.0=3Dchilds0 \ + -incoming tcp:0.0.0.0:9998 + + +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', 'da= ta': {'host': '0.0.0.0', 'port': '9999'} } } } +{'execute': 'nbd-server-add', 'arguments': {'device': 'parent0', 'writable= ': true } } =20 Note: a. The qmp command nbd-server-start and nbd-server-add must be run @@ -182,44 +212,113 @@ Note: same. c. It is better to put active disk and hidden disk in ramdisk. =20 -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=3Dreplication,m= ode=3Dprimary,file.driver=3Dnbd,file.host=3Dxx.xx.xx.xx,file.port=3D8889,fi= le.export=3Dsecondary-disk0,node-name=3Dnbd_client0'}} -{ 'execute':'x-blockdev-change', 'arguments':{'parent': 'primary-disk0', '= node': 'nbd_client0' } } -{ 'execute': 'migrate-set-capabilities', - 'arguments': {'capabilities': [ {'capability': 'x-colo', 'state': tr= ue } ] } } -{ 'execute': 'migrate', 'arguments': {'uri': 'tcp:xx.xx.xx.xx:8888' } } +{'execute': 'human-monitor-command', 'arguments': {'command-line': 'drive_= add -n buddy driver=3Dreplication,mode=3Dprimary,file.driver=3Dnbd,file.hos= t=3D127.0.0.2,file.port=3D9999,file.export=3Dparent0,node-name=3Dreplicatio= n0'}} +{'execute': 'x-blockdev-change', 'arguments':{'parent': 'colo-disk0', 'nod= e': 'replication0' } } +{'execute': 'migrate-set-capabilities', 'arguments': {'capabilities': [ {'= capability': 'x-colo', 'state': true } ] } } +{'execute': 'migrate', 'arguments': {'uri': 'tcp:127.0.0.2:9998' } } =20 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. =20 -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 replicatio= n" + +=3D=3D Primary Failover =3D=3D +The Secondary died, resume on the Primary + +{'execute': 'x-blockdev-change', 'arguments':{ 'parent': 'colo-disk0', 'ch= ild': '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' } + +=3D=3D Secondary Failover =3D=3D +The Primary died, resume on the Secondary and prepare to become the new Pr= imary + +{'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': {'typ= e': 'socket', 'data': {'addr': { 'type': 'inet', 'data': { 'host': '0.0.0.0= ', 'port': '9003' } }, 'server': true } } } } +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare1', 'backend': {'ty= pe': 'socket', 'data': {'addr': { 'type': 'inet', 'data': { 'host': '0.0.0.= 0', 'port': '9004' } }, 'server': true } } } } +{'execute': 'chardev-add', 'arguments':{ 'id': 'compare0', 'backend': {'ty= pe': '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': '12= 7.0.0.1', 'port': '9005' } }, 'server': false } } } } + +=3D=3D Primary resume replication =3D=3D +Resume replication after new Secondary is up. + +Start the new Secondary (Steps 2 and 3 above), then on the Primary: +{'execute': 'drive-mirror', 'arguments':{ 'device': 'colo-disk0', 'job-id'= : 'resync', 'target': 'nbd://127.0.0.2:9999/parent0', 'mode': 'existing', '= format': 'raw', 'sync': 'full'} } + +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=3Dreplication,mode=3Dprimary,file.driver=3Dnbd,file.hos= t=3D127.0.0.2,file.port=3D9999,file.export=3Dparent0,node-name=3Dreplicatio= n0'}} +{'execute': 'x-blockdev-change', 'arguments':{ 'parent': 'colo-disk0', 'no= de': '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': 'compar= e_out' } } } +{'execute': 'object-add', 'arguments':{ 'qom-type': 'filter-redirector', '= id': 'redire1', 'props': { 'netdev': 'hn0', 'queue': 'rx', 'outdev': 'compa= re0' } } } +{'execute': 'object-add', 'arguments':{ 'qom-type': 'iothread', 'id': 'iot= hread1' } } +{'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:127.0.0.2:9998' } } + +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': 'id=3Drew0'" Options. See below. + +=3D=3D Secondary resume replication =3D=3D +Become Primary and resume replication after new Secondary is up. Note +that now 127.0.0.1 is the Secondary and 127.0.0.2 is the Primary. + +Start the new Secondary (Steps 2 and 3 above, but with primary_ip=3D127.0.= 0.2), +then on the old Secondary: +{'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' } } =20 -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 detec= t this -change. +{'execute': 'human-monitor-command', 'arguments':{ 'command-line': 'drive_= add -n buddy driver=3Dreplication,mode=3Dprimary,file.driver=3Dnbd,file.hos= t=3D127.0.0.1,file.port=3D9999,file.export=3Dparent0,node-name=3Dreplicatio= n0'}} +{'execute': 'x-blockdev-change', 'arguments':{ 'parent': 'colo-disk0', 'no= de': 'replication0' } } =20 -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': 'driv= e_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=3Drew0', 'netdev': 'h= n0', 'queue': 'tx', 'outdev': 'mirror0' } } } +{'execute': 'object-add', 'arguments':{ 'qom-type': 'filter-redirector', '= id': 'redire0', 'props': { 'insert': 'before', 'position': 'id=3Drew0', 'ne= tdev': 'hn0', 'queue': 'rx', 'indev': 'compare_out' } } } +{'execute': 'object-add', 'arguments':{ 'qom-type': 'filter-redirector', '= id': 'redire1', 'props': { 'insert': 'before', 'position': 'id=3Drew0', 'ne= tdev': 'hn0', 'queue': 'rx', 'outdev': 'compare0' } } } +{'execute': 'object-add', 'arguments':{ 'qom-type': 'iothread', 'id': 'iot= hread1' } } +{'execute': 'object-add', 'arguments':{ 'qom-type': 'colo-compare', 'id': = 'comp0', 'props': { 'primary_in': 'compare0-0', 'secondary_in': 'compare1',= 'outdev': 'compare_out0', 'iothread': 'iothread1' } } } =20 -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' } } =20 =3D=3D TODO =3D=3D -1. Support continuous VM replication. -2. Support shared storage. -3. Develop the heartbeat part. -4. Reduce checkpoint VM=E2=80=99s downtime while doing checkpoint. +1. Support shared storage. +2. Develop the heartbeat part. +3. Reduce checkpoint VM=E2=80=99s 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 speculat= ive 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. =20 +7) The secondary also has a quorum node, so after secondary failover it +can become the new primary and continue replication. + + =3D=3D Failure Handling =3D=3D 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). =20 Secondary: -drive if=3Dnone,driver=3Draw,file.filename=3D1.raw,id=3Dcolo1 \ - -drive if=3Dxxx,id=3Dtopxxx,driver=3Dreplication,mode=3Dsecondary,top-id= =3Dtopxxx\ + -drive if=3Dnone,id=3Dchilds1,driver=3Dreplication,mode=3Dsecondary,top-= id=3Dchilds1 file.file.filename=3Dactive_disk.qcow2,\ file.driver=3Dqcow2,\ file.backing.file.filename=3Dhidden_disk.qcow2,\ file.backing.driver=3Dqcow2,\ file.backing.backing=3Dcolo1 + -drive if=3Dxxx,driver=3Dquorum,read-pattern=3Dfifo,id=3Dtop-disk1,\ + vote-threshold=3D1,children.0=3Dchilds1 =20 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' } =20 +Promote Secondary to Primary: + see COLO-FT.txt + TODO: -1. Continuous block replication -2. Shared disk +1. Shared disk --=20 2.20.1