[dm-devel] [Question] multipathd.service start failed when /var/run isn't mount

[lixiaokeng]

On 2021/7/23 5:42, Benjamin Marzinski wrote:
> On Thu, Jul 22, 2021 at 10:51:22AM +0800, lixiaokeng wrote:
>> When we enable multipathd.service with systemctl and reboot,
>> multipathd doesn't start and log "failed to create pidfile".
>>
>> The reason is following:
>>
>> The RUN is /var/run in multipath-tools. When we start linux, we
>> mount a disk to /var. So if multipathd.service start before mount,
>> it will fail to activate.(If mount firstly, multipathd will start
>> successfully)
>>
>> The RUN is defined in Makefile.inc:
>>
>> ifndef RUN
>>         ifeq ($(shell test -L /var/run -o ! -d /var/run && echo 1),1)
>>                 RUN=run
>>         else
>>                 RUN=var/run
>>         endif
>> endif
>>
>> Can it always be defined as run?
> 
> I believe all modern distributions make /var/run a symlink to /run.
> However, if that's the case, then I don't understand why you are running
> into this issue at all, since multipath should be using /run. What
> multipath packages are you using?
Yes, there is a symlink to /run in /var. But it is in the disk (such as
sdb) mounted on /var actually. When reboot, systemd start multipathd
service firstly then mount sdb to /var. In this way, the multipath
service will not start.

After sdb mounted to /var, we can start multipathd service successfully.

> 
> -Ben
> 
>>
>> Regards,
>> Lixiaokeng
> 
> .
>