[dm-devel] [PATCH] multipath-tools: convert back HUAWEI/XSG1 to multibus

[Martin Wilck]

On Sat, 2021-03-27 at 00:50 +0100, Xose Vazquez Perez wrote:
> On 3/26/21 8:55 PM, Martin Wilck wrote:
> 
> > On Fri, 2021-03-26 at 19:10 +0100, Xose Vazquez Perez wrote:
> 
> > > 1.- It's the official vendor recommendation, and people trust it
> > > blindly
> > >       above the multipath-tools setting. Sad but true.
> > >       So it's going to be manually replaced by the vendor's
> > > config.
> > 
> > Some users are like that, sure. But if that was generally true, we
> > wouldn't need to adapt our defaults, because everyone would copy
> > the
> > configs from the vendor manuals.
> 
> I would like that HUAWEI guys fix their docs. Or much better,
> make their arrays always work in ALUA mode. I do not see what the
> problem is. Other vendors do this with A/A arrays.
> 
> > > 2.- It generates an awful warning:
> > > 
> > >       [This is SLES 12SP5 with 4.12.14-122.54-default on x86_64
> > >       and multipath-tools-0.7.9+195+suse.16740c5-3.6.1.x86_64]
> > > 
> > > # multipath -ll
> > > 
> > > Mar 26 18:34:46 | sdi: prio = const (setting: emergency fallback
> > > -
> > > alua failed)
> > > Mar 26 18:34:46 | sdj: prio = const (setting: emergency fallback
> > > -
> > > alua failed)
> > > Mar 26 18:34:46 | sdk: prio = const (setting: emergency fallback
> > > -
> > > alua failed)
> > > Mar 26 18:34:46 | sdl: prio = const (setting: emergency fallback
> > > -
> > > alua failed)
> > > 36a35324100e5x5d408d0526600000001 dm-1 HUAWEI,XSG1
> > > size=10G features='0' hwhandler='0' wp=rw
> > > `-+- policy='service-time 0' prio=1 status=enabled
> > >     |- 0:0:4:1 sdi 8:128 active ready running
> > >     |- 0:0:5:1 sdj 8:144 active ready running
> > >     |- 1:0:4:1 sdk 8:160 active ready running
> > >     `- 1:0:5:1 sdl 8:176 active ready running
> > > 
> > >       No nice, mainly for people without knowledge of mpt
> > > internals.
> > 
> > The problem is that the prioritizer was explicitly set to "alua".
> > Therefore multipathd warns, because the configured setting couldn't
> > be
> > applied. We could just drop that line, alua would still be selected
> > by
> > the autodetection if it was supported, and the message wouldn't be
> > printed any more otherwise. Setting "multibus" explicitly isn't
> > necessary.
> > 
> > Can we agree on that?
> 
> Something like the patch below?
> It's a frankenstein config, and ALUA should only work for kernels >=
> 4.3

Yes. That's good enough IMO. People running older kernels can use the
explicit config (and likely have been doing so anyway).

Add a comment explaining the "hypermetro" dependency, perhaps.

Martin


> 
> ------
>  From 47c505f853b37c38d847b411fc7ba763c61ad87b Mon Sep 17 00:00:00
> 2001
> From: Xose Vazquez Perez <xose.vazquez at gmail.com>
> Date: Sat, 27 Mar 2021 00:13:57 +0100
> Subject: [PATCH] multipath-tools: make HUAWEI/XSG1 config work with
> alua and multibus
> X-Patchwork-Bot: notify
> 
> And add recommended no_path_retry and pgfailback values.
> 
> Info from:
> - RHEL 
> https://download.huawei.com/edownload/e/download.do?actionFlag=download&nid=EDOC1100113070&partNo=6001&mid=SUPE_DOC&_t=1612885511000
> - SLES 
> https://download.huawei.com/edownload/e/download.do?actionFlag=download&nid=EDOC1100117892&partNo=6001&mid=SUPE_DOC&_t=1612885538000
> 
> - without HyperMetro:
> vendor "HUAWEI"
> product "XSG1"
> path_grouping_policy multibus
> no_path_retry 15
> 
> - with HyperMetro:
> vendor "HUAWEI"
> product "XSG1"
> path_grouping_policy group_by_prio
> prio alua
> failback immediate
> no_path_retry 15
> 
> ALUA is only used with HyperMetro(cluster of two arrays).
> 
> Suggested-by: Martin Wilck <mwilck at suse.com>
> Cc: Zhouweigang (Jack) <zhouweigang09 at huawei.com>
> Cc: Zou Ming <zouming.zouming at huawei.com>
> Cc: Benjamin Marzinski <bmarzins at redhat.com>
> Cc: Martin Wilck <mwilck at suse.com>
> Cc: Christophe Varoqui <christophe.varoqui at opensvc.com>
> Cc: DM-DEVEL ML <dm-devel at redhat.com>
> Signed-off-by: Xose Vazquez Perez <xose.vazquez at gmail.com>
> ---
>   libmultipath/hwtable.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
> index 58fa7387..f09af30e 100644
> --- a/libmultipath/hwtable.c
> +++ b/libmultipath/hwtable.c
> @@ -1082,7 +1082,8 @@ static struct hwentry default_hw[] = {
>                 .vendor        = "HUAWEI",
>                 .product       = "XSG1",
>                 .pgpolicy      = GROUP_BY_PRIO,
> -               .prio_name     = PRIO_ALUA,
> +               .pgfailback    = -FAILBACK_IMMEDIATE,
> +               .no_path_retry = 15,
>         },
>         /*
>          * Kove