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

[Benjamin Marzinski <bmarzins@redhat.com>]

On Wed, Sep 10, 2025 at 09:41:57PM +0200, Xose Vazquez Perez wrote:
> Source: https://dl.acronis.com/u/software-defined/html/AcronisCyberInfrastructure_3_5_users_guide_en-US/accessing-iscsi/accessing-iscsi-targets-from-linux.html
> 
> Cc: Martin Wilck <mwilck@suse.com>
> Cc: Benjamin Marzinski <bmarzins@redhat.com>
> Cc: Christophe Varoqui <christophe.varoqui@opensvc.com>
> Cc: DM_DEVEL-ML <dm-devel@lists.linux.dev>
> Signed-off-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
> ---
>  libmultipath/hwtable.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
> index 1a78c36d..12e10577 100644
> --- a/libmultipath/hwtable.c
> +++ b/libmultipath/hwtable.c
> @@ -1371,6 +1371,21 @@ static struct hwentry default_hw[] = {
>  		.pgpolicy      = GROUP_BY_SERIAL,
>  		.no_path_retry = 30,
>  	},
> +	/*
> +	 * Acronis
> +	 */
> +	{
> +		// Cyber Infrastructure
> +		.vendor        = "VSTORAGE",
> +		.product       = "VSTOR-DISK",
> +		.prio_name     = PRIO_ALUA,
> +		.pgpolicy      = GROUP_BY_NODE_NAME,
> +		.detect_prio   = DETECT_PRIO_OFF,
> +		.features      = "2 pg_init_retries 50",
> +		.pgfailback    = -FAILBACK_FOLLOWOVER,

I'm not sure about the pgfailback setting. the FAILBACK_FOLLOWOVER mode
is not something that is really needed for a specific array type. It
works like FAILOVER_IMMEDIATE, but it's designed to work so that if
multiple nodes are using the same multipath device, and one of them
loses access to the highest priority pathgroup but the others don't,
multipath won't keep switching pathgroups back and forth. The nodes that
can see the higher priority pathgroup won't automatically switch back to
it, since they weren't the ones that switched away from it. So the
setting is more for a specific use case, and not a specific array type.

On the other hand, it is what the vendor tested, and with a single
machine accessing the multipath device, you usually only switch away
from the highest priority pathgroup because you lost access to all the
paths in it. So it usually won't get stuck on a lower priority pathgroup
while a higher priority one is usable, although that could happen. 

Thoughts?

-Ben

> +		.flush_on_last_del = FLUSH_ALWAYS,
> +		.no_path_retry = NO_PATH_RETRY_QUEUE,
> +	},
>  	/*
>  	 * EOL
>  	 */
> -- 
> 2.51.0