Re: [PATCH v2 8/8] qemu-colo.rst: Simplify the block replication setup

[Peter Xu <peterx@redhat.com>]

On Sat, Jan 17, 2026 at 03:09:15PM +0100, Lukas Straub wrote:
> 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'.
> 
> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> Tested-by: Lukas Straub <lukasstraub2@web.de>

We can drop this line; Tested-by is normally not used on one's own patch.
Proposer should always test one's own patch..

I'll leave it to Chen and others to review this patch.  Please consider
copy Zhijian and Dave when you repost; you'll get higher chance to get it
reviewed.

Thanks,

> ---
>  docs/system/qemu-colo.rst | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/docs/system/qemu-colo.rst b/docs/system/qemu-colo.rst
> index 2052e207e57afdd3ab3ab1a447d55f5e2e5b5b87..7e361998d871b2c9a0e8065a15c004a9d841958b 100644
> --- a/docs/system/qemu-colo.rst
> +++ b/docs/system/qemu-colo.rst
> @@ -233,8 +233,8 @@ Note:
>  **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=127.0.0.2,file.port=9999,file.export=parent0,node-name=replication0"}}
> -    {"execute": "x-blockdev-change", "arguments":{"parent": "colo-disk0", "node": "replication0" } }
> +    {"execute": "blockdev-add", "arguments": {"driver": "nbd", "node-name": "nbd0", "server": {"type": "inet", "host": "127.0.0.2", "port": "9999"}, "export": "parent0", "detect-zeroes": "on"} }
> +    {"execute": "x-blockdev-change", "arguments":{"parent": "colo-disk0", "node": "nbd0" } }
>      {"execute": "migrate-set-capabilities", "arguments": {"capabilities": [ {"capability": "x-colo", "state": true } ] } }
>      {"execute": "migrate", "arguments": {"uri": "tcp:127.0.0.2:9998" } }
>  
> @@ -262,7 +262,7 @@ 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": "blockdev-del", "arguments": {"node-name": "nbd0"} }
>      {"execute": "object-del", "arguments":{ "id": "comp0" } }
>      {"execute": "object-del", "arguments":{ "id": "iothread1" } }
>      {"execute": "object-del", "arguments":{ "id": "m0" } }
> @@ -302,8 +302,8 @@ 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=127.0.0.2,file.port=9999,file.export=parent0,node-name=replication0"}}
> -    {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "replication0" } }
> +    {"execute": "blockdev-add", "arguments": {"driver": "nbd", "node-name": "nbd0", "server": {"type": "inet", "host": "127.0.0.2", "port": "9999"}, "export": "parent0", "detect-zeroes": "on"} }
> +    {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "nbd0" } }
>  
>      {"execute": "object-add", "arguments":{ "qom-type": "filter-mirror", "id": "m0", "netdev": "hn0", "queue": "tx", "outdev": "mirror0" } }
>      {"execute": "object-add", "arguments":{ "qom-type": "filter-redirector", "id": "redire0", "netdev": "hn0", "queue": "rx", "indev": "compare_out" } }
> @@ -334,8 +334,8 @@ 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,file.port=9999,file.export=parent0,node-name=replication0"}}
> -    {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "replication0" } }
> +    {"execute": "blockdev-add", "arguments": {"driver": "nbd", "node-name": "nbd0", "server": {"type": "inet", "host": "127.0.0.1", "port": "9999"}, "export": "parent0", "detect-zeroes": "on"} }
> +    {"execute": "x-blockdev-change", "arguments":{ "parent": "colo-disk0", "node": "nbd0" } }
>  
>      {"execute": "object-add", "arguments":{ "qom-type": "filter-mirror", "id": "m0", "insert": "before", "position": "id=rew0", "netdev": "hn0", "queue": "tx", "outdev": "mirror0" } }
>      {"execute": "object-add", "arguments":{ "qom-type": "filter-redirector", "id": "redire0", "insert": "before", "position": "id=rew0", "netdev": "hn0", "queue": "rx", "indev": "compare_out" } }
> 
> -- 
> 2.39.5
> 

-- 
Peter Xu