Re: [PATCH 1/3] multipath-tools: add Acronis Cyber Infrastructure to hwtable

[Xose Vazquez Perez <xose.vazquez@gmail.com>]

On 9/23/25 8:22 AM, Martin Wilck wrote:

> On Mon, 2025-09-22 at 20:38 +0200, Martin Wilck wrote:

>> Not necessarily. path_group_prio_update() calculates the average of
>> the
>> path priorities in the group. With ALUA and groups of 6+ paths, an
>> optimized group with one healthy path will have a lower prio (8) than
>> a
>> non-optimized group with all healthy paths (10). In such a case it
>> could happen that multipathd switches to the non-optimized group and
>> never switches back.
> 
> Sorry, this example was incorrect. Only paths in UP or GHOST states are
> counted in for the PG prio. In this example the optimized group would
> still have p = 50, and what I described would not occur.
> 
> The example would be correct if the 5 non-"healthy" paths in the first
> PG were in standby aka GHOST state (resulting in p = 55 / 6 = 9). But
> that's a very different scenario, and highly theoretical.
> 
>> I would suggest setting FAILBACK_IMMEDIATE instead. It's well
>> documented that FOLLOWOVER is only for cluster environments.
> 
> Despite the wrong example, I still think FAILBACK_IMMEDIATE makes
> more sense as a general default. We can add a comment about the vendor
> recommendations.

I sent a new patch with that fixed.