11:44 p.m.
On Mon, Feb 01, 2021 at 03:47:32PM +0100, Gianluca Cecchi wrote:
On Mon, Feb 1, 2021 at 3:10 PM Nir Soffer <nsoffer(a)redhat.com>
wrote:
[snip]
> 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?
>
I was using Equallogic kind of storage since oVirt 3.6, so CentoOS/RHEL 6,
and it has never been inside the multipath database as far as I remember.
But I don't know why.
The parameters I put was from latest EQL best practices, but they was
updated at CentOS 7 time.
I would like to use the same parameters in CentOS 8 now and see if they
works ok.
PS line of EQL is somehow deprecated (in the sense of no new features and
so on..) but anyway still supported
>
> > 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.
>
Those were the recommended values from EQL
Latest is dated April 2016 when 8 not out yet:
http://downloads.dell.com/solutions/storage-solution-resources/(3199-CD-L...
Thanks for this link. I'll add this to the default built-ins.
-Ben
>
> Ben: please correct me if needed
>
> > 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.
>
You are right; I see the value of 16 both in defaults and overrides. But I
put it also inside the device section during my tests in doubt it was not
picked up in the hope to see similar output as in CentOS 7:
36090a0c8d04f21111fc4251c7c08d0a3 dm-14 EQLOGIC ,100E-00
size=2.4T features='1 queue_if_no_path' hwhandler='0' wp=rw
where you notice the hwhandler='0'
Originally I remember the default value for no_path_retry was 4 but
probably it has been changed in 4.4 to 16, correct?
If I want to see the default that vdsm would create from scratch should I
see inside
/usr/lib/python3.6/site-packages/vdsm/tool/configurators/multipath.py of my
version?
On my system with vdsm-python-4.40.40-1.el8.noarch I have this inside that
file
_NO_PATH_RETRY = 16
>
> 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
>
> > }
>
Yes I set this:
# cat /etc/vdsm/vdsm.conf.d/99-FooIO.conf
# Configuration for FooIO storage.
[sanlock]
# Set renewal timeout to 80 seconds
# (8 * io_timeout == 80).
io_timeout = 10
And for another environment with Netapp MetroCluster and 2 different sites
(I'm with RHV there...) I plan to set no_path_retry to 24 and io_timeout to
15, to manage disaster recovery scenarios and planned maintenance with
Netapp node failover through sites taking potentially up to 120 seconds.
> 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.
>
> > 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
>
>
I would like just to be confident about the no_path_retry setting, because
the multipath output, also with -v2, -v3, -v4 seems not so clear to me
In 7 (as Benjamin suggested 4 years ago.. ;-) I have this:
# multipath -r -v3 | grep no_path_retry
Feb 01 15:45:27 | 36090a0d88034667163b315f8c906b0ac: no_path_retry = 4
(config file default)
Feb 01 15:45:27 | 36090a0c8d04f21111fc4251c7c08d0a3: no_path_retry = 4
(config file default)
On CentOS 8.3 I get only standard error...:
# multipath -r -v3
Feb 01 15:46:32 | set open fds limit to 8192/262144
Feb 01 15:46:32 | loading /lib64/multipath/libchecktur.so checker
Feb 01 15:46:32 | checker tur: message table size = 3
Feb 01 15:46:32 | loading /lib64/multipath/libprioconst.so prioritizer
Feb 01 15:46:32 | foreign library "nvme" loaded successfully
Feb 01 15:46:32 | delegating command to multipathd
Thanks,
Gianluca