[dm-devel] multipath with SAS and FC.

[Xose Vazquez Perez]

On 3/1/21 2:44 PM, bchatelain at cines.fr wrote:

> I try to use multipath with SAS disk, transported by Fiber Channel, on
> Dell Compellent.
> My volume is detected on 2x R440 PowerEdge hosted by Centos 8 and
> orchestrated by oVirt.
> [...]
> # multipath -ll
> 36000d31003d5c2000000000000000010 dm-3 COMPELNT,Compellent Vol
> size=1.5T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
> `-+- policy='service-time 0' prio=25 status=active
>     |- 1:0:0:2 sdb 8:16 active ready running
>     `- 1:0:1:2 sdc 8:32 failed ready running   -- looping failed/ready

The default mpt config for "COMPELNT/Compellent Vol" is already "multibus".
There is no need to add a custom config to /etc/multipath.conf.

Try:
# save old configs
mv /etc/multipath.conf /etc/_multipath.conf-$(date +%s)
cp -a /etc/multipath/wwids /etc/multipath/_wwids-$(date +%s)
# reconfig mp
mpathconf --enable --user_friendly_names n
multipath -W
systemctl enable multipathd.service
# recreate initrd, and reboot the system
dracut -f
init 6


If the default mode of "COMPELNT/Compellent Vol" arrays WERE CHANGED to ALUA,
(dmesg -T | grep -i alua). The /etc/multipath.conf file must contain:

devices {
	device {
		vendor "COMPELNT"
		product "Compellent Vol"
		path_grouping_policy "group_by_prio"
		prio "alua"
		failback "immediate"
		no_path_retry 30
	}
}

Follow the same steps, but before "dracut -f" add that config to /etc/multipath.conf