Re: [Qemu-devel] [PATCH RFC v2 1/6] docs/block-replication: Add description for shared-disk case

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, Dec 05, 2016 at 04:34:59PM +0800, zhanghailiang wrote:
> +Issue qmp command:
> +  { 'execute': 'blockdev-add',
> +    'arguments': {
> +        'driver': 'replication',
> +        'node-name': 'rep',
> +        'mode': 'primary',
> +        'shared-disk-id': 'primary_disk0',
> +        'shared-disk': true,
> +        'file': {
> +            'driver': 'nbd',
> +            'export': 'hidden_disk0',
> +            'server': {
> +                'type': 'inet',
> +                'data': {
> +                    'host': 'xxx.xxx.xxx.xxx',
> +                    'port': 'yyy'
> +                }
> +            }

block/nbd.c does have good error handling and recovery in case there is
a network issue.  There are no reconnection attempts or timeouts that
deal with a temporary loss of network connectivity.

This is a general problem with block/nbd.c and not something to solve in
this patch series.  I'm just mentioning it because it may affect COLO
replication.

I'm sure these limitations in block/nbd.c can be fixed but it will take
some effort.  Maybe block/sheepdog.c, net/socket.c, and other network
code could also benefit from generic network connection recovery.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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