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

[Xose Vazquez Perez]

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

------
 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
-- 
2.30.2