qemu-colo.rst: Simplify the block replication setup
On the primary side we don't actually need the replication block driver, since it only passes trough all IO. So simplify the setup and also use 'blockdev-add' instead of 'human-monitor-command'. This is how my clients use colo in production. Reviewed-by: Fabiano Rosas <farosas@suse.de> Signed-off-by: Lukas Straub <lukasstraub2@web.de> Link: https://lore.kernel.org/qemu-devel/20260302-colo_unit_test_multifd-v11-17-d653fb3b1d80@web.de Signed-off-by: Fabiano Rosas <farosas@suse.de>
Lukas Straub committed
Mar 2, 2026 at 12:45 UTC
2a402535ba2da6bfd2d84872283740486bd940de
1 file changed
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docs/system/qemu-colo.rst
+7
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@@ -242,8 +242,8 @@ Note:
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**4.** On Primary VM's QEMU monitor, issue command::
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{"execute":"qmp_capabilities"}
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- {"execute": "human-monitor-command", "arguments": {"command-line": "drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.2,file.port=9999,file.export=parent0,node-name=replication0"}}
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- {"execute": "x-blockdev-change", "arguments":{"parent": "colo-disk0", "node": "replication0" } }
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+ {"execute": "blockdev-add", "arguments": {"driver": "nbd", "node-name": "nbd0", "server": {"type": "inet", "host": "127.0.0.2", "port": "9999"}, "export": "parent0", "detect-zeroes": "on"} }
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+ {"execute": "x-blockdev-change", "arguments":{"parent": "colo-disk0", "node": "nbd0" } }
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{"execute": "migrate-set-capabilities", "arguments": {"capabilities": [ {"capability": "x-colo", "state": true } ] } }
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{"execute": "migrate", "arguments": {"uri": "tcp:127.0.0.2:9998" } }
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@@ -271,7 +271,7 @@ Primary Failover
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The Secondary died, resume on the Primary::
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{"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "child": "children.1"} }
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- {"execute": "human-monitor-command", "arguments":{ "command-line": "drive_del replication0" } }
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+ {"execute": "blockdev-del", "arguments": {"node-name": "nbd0"} }
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{"execute": "object-del", "arguments":{ "id": "comp0" } }
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{"execute": "object-del", "arguments":{ "id": "iothread1" } }
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{"execute": "object-del", "arguments":{ "id": "m0" } }
@@ -311,8 +311,8 @@ Wait until disk is synced, then::
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{"execute": "stop"}
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{"execute": "block-job-cancel", "arguments":{ "device": "resync"} }
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- {"execute": "human-monitor-command", "arguments":{ "command-line": "drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.2,file.port=9999,file.export=parent0,node-name=replication0"}}
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- {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "replication0" } }
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+ {"execute": "blockdev-add", "arguments": {"driver": "nbd", "node-name": "nbd0", "server": {"type": "inet", "host": "127.0.0.2", "port": "9999"}, "export": "parent0", "detect-zeroes": "on"} }
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+ {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "nbd0" } }
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{"execute": "object-add", "arguments":{ "qom-type": "filter-mirror", "id": "m0", "netdev": "hn0", "queue": "tx", "outdev": "mirror0" } }
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{"execute": "object-add", "arguments":{ "qom-type": "filter-redirector", "id": "redire0", "netdev": "hn0", "queue": "rx", "indev": "compare_out" } }
@@ -343,8 +343,8 @@ Wait until disk is synced, then::
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{"execute": "stop"}
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{"execute": "block-job-cancel", "arguments":{ "device": "resync" } }
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- {"execute": "human-monitor-command", "arguments":{ "command-line": "drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,file.host=127.0.0.1,file.port=9999,file.export=parent0,node-name=replication0"}}
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- {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "replication0" } }
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+ {"execute": "blockdev-add", "arguments": {"driver": "nbd", "node-name": "nbd0", "server": {"type": "inet", "host": "127.0.0.1", "port": "9999"}, "export": "parent0", "detect-zeroes": "on"} }
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+ {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "nbd0" } }
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{"execute": "object-add", "arguments":{ "qom-type": "filter-mirror", "id": "m0", "insert": "before", "position": "id=rew0", "netdev": "hn0", "queue": "tx", "outdev": "mirror0" } }
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{"execute": "object-add", "arguments":{ "qom-type": "filter-redirector", "id": "redire0", "insert": "before", "position": "id=rew0", "netdev": "hn0", "queue": "rx", "indev": "compare_out" } }