[PATCH docs] qdevice: correct qdevice partition tie breaking section.

[PATCH docs] qdevice: correct qdevice partition tie breaking section.

[Manuel Federanko]

The partition that gets a vote is not randomly chosen, but depends on
the configuration of the qdevice in corosync.conf.

A partner asked about predictable behavior for vote casting by the
QDevice. The documentation of corosync and ours didn't align.

Setting tie_breaker influences how a partition is chosen for votes,
which was tested with a 2-node test-cluster.

Signed-off-by: Manuel Federanko <m.federanko@proxmox.com>
---
 pvecm.adoc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pvecm.adoc b/pvecm.adoc
index 0ed1bd2..899a4de 100644
--- a/pvecm.adoc
+++ b/pvecm.adoc
@@ -1266,8 +1266,10 @@ Tie Breaking
 ^^^^^^^^^^^^
 
 In case of a tie, where two same-sized cluster partitions cannot see each other
-but can see the QDevice, the QDevice chooses one of those partitions randomly
-and provides a vote to it.
+but can see the QDevice, the QDevice chooses the partition which has
+the lowest node id and provides a vote to it. This behavior can be tuned with
+the configuration option `tie_breaker` (see `man corosync-qdevice` for more
+information) and requires a restart of `corosync-qdevice.service` on all nodes.
 
 Possible Negative Implications
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-- 
2.47.3

Re: [PATCH docs] qdevice: correct qdevice partition tie breaking section.

[Maximiliano Sandoval]

Manuel Federanko <m.federanko@proxmox.com> writes:

> The partition that gets a vote is not randomly chosen, but depends on
> the configuration of the qdevice in corosync.conf.
>
> A partner asked about predictable behavior for vote casting by the
> QDevice. The documentation of corosync and ours didn't align.
>
> Setting tie_breaker influences how a partition is chosen for votes,
> which was tested with a 2-node test-cluster.
>
> Signed-off-by: Manuel Federanko <m.federanko@proxmox.com>
> ---
>  pvecm.adoc | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/pvecm.adoc b/pvecm.adoc
> index 0ed1bd2..899a4de 100644
> --- a/pvecm.adoc
> +++ b/pvecm.adoc
> @@ -1266,8 +1266,10 @@ Tie Breaking
>  ^^^^^^^^^^^^
>  
>  In case of a tie, where two same-sized cluster partitions cannot see each other
> -but can see the QDevice, the QDevice chooses one of those partitions randomly
> -and provides a vote to it.
> +but can see the QDevice, the QDevice chooses the partition which has
> +the lowest node id and provides a vote to it. This behavior can be tuned with
> +the configuration option `tie_breaker` (see `man corosync-qdevice` for more
> +information) and requires a restart of `corosync-qdevice.service` on all nodes.
>  
>  Possible Negative Implications
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I would personally only mention the man page so to avoid running out of
sync, but this looks good to me as-is.

Reviewed-by: Maximiliano Sandoval <m.sandoval@proxmox.com>

-- 
Maximiliano