10:39 p.m.
On Mon, Feb 01, 2021 at 04:10:02PM +0200, Nir Soffer wrote:
On Mon, Feb 1, 2021 at 1:55 PM Gianluca Cecchi
<gianluca.cecchi(a)gmail.com> wrote:
>
> On Sat, Jan 30, 2021 at 6:05 PM Strahil Nikolov <hunter86_bg(a)yahoo.com>
wrote:
>>
>> So you created that extra conf with this content but it didn't work ?
>> multipath -v4 could hint you why it was complaining.
>>
>>
>> Best Regards,
>> Strahil Nikolov
>>
>
> Ok, I missed the surrounding root part
>
> devices {
>
> }
It seems that we need more examples in multpath.conf file
installed by vdsm.
> Apparently "multipathd show config" didn't complain...
> Now I put also that and it seems to work, thanks for pointing it
>
> So at the end I have the multipath.conf default file installed by vdsm (so without
the # PRIVATE line)
> and this in /etc/multipath/conf.d/eql.conf
>
> devices {
> device {
> vendor "EQLOGIC"
> product "100E-00"
Ben, why is this device missing from multipath builtin devices?
We usually get these from the device vendors themselves, or at least get
their blessing. But it's cerainly possible to add configs even without
the vendor's blessing.
> path_selector "round-robin 0"
> path_grouping_policy multibus
> path_checker tur
> rr_min_io_rq 10
> rr_weight priorities
> failback immediate
> features "0"
This is never needed, multipath generates this value.
Ben: please correct me if needed
That's not exactly correct. Multipath will override the "queue_if_no_path"
and "retain_attached_hw_handler" featurs, based on the values of the
retain_attached_hw_handler and no_path_retry options. It will leave any
other features alone. So, features like "pg_init_retries" and
"pg_init_delay_seconds" still need to be specified using the features
option. But you certianly don't ever need to specify a blank featues
line, not that it hurts anything.
> no_path_retry 16
I'm don't think that you need this, since you should inherit the value from vdsm
multipath.conf, either from the "defaults" section, or from the
"overrides" section.
You must add no_path_retry here if you want to use another value, and you don't
want to use vdsm default value.
Note that if you use your own value, you need to match it to sanlock io_timeout.
See this document for more info:
https://github.com/oVirt/vdsm/blob/master/doc/io-timeouts.md
> }
> }
>
> Recreated initrd and rebooted the host and activated it without further problems.
> And "multipathd show config" confirms it.
Yes, this is the recommended way to configure multipath, thanks Strahil for the
good advice!
> But still I see this
>
> # multipath -l
> 36090a0c8d04f21111fc4251c7c08d0a3 dm-13 EQLOGIC,100E-00
> size=2.4T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
> `-+- policy='round-robin 0' prio=0 status=active
> |- 16:0:0:0 sdc 8:32 active undef running
> `- 18:0:0:0 sde 8:64 active undef running
> 36090a0d88034667163b315f8c906b0ac dm-12 EQLOGIC,100E-00
> size=2.0T features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
> `-+- policy='round-robin 0' prio=0 status=active
> |- 15:0:0:0 sdb 8:16 active undef running
> `- 17:0:0:0 sdd 8:48 active undef running
>
> that lets me think I'm not using the no_path_retry setting, but
queue_if_no_path... I could be wrong anyway..
Not this is expected. What is means, if I understand multipath
behavior correctly,
that the device queue data for no_path_retry * polling_internal seconds when all
paths failed. After that the device will fail all pending and new I/O
until at least
one path is recovered.
Correct. This is just showing you the current configuration that the
kernel is using. The kernel doesn't know anything about no_path_retry.
That is something that multipathd uses internally. It just switches on
and off the queue_if_no_path feature at the appropriate time.
Currently, you have usable paths, and so the queue_if_no_path features
should obviously be on. Once you've lost all your paths, and they've
stayed down path the no_path_retry limit, multipathd will remove this
feature from the kernel device. When a path is then restored, it will
add the feature back.
> How to verify for sure (without dropping the paths, at least at
the moment) from the config?
> Any option with multipath and/or dmsetup commands?
multipath show config -> find your device section, it will show the current
value for no_path_retry.
Nir