On Mon, Feb 01, 2021 at 03:47:32PM +0100, Gianluca Cecchi wrote:
> On Mon, Feb 1, 2021 at 3:10 PM Nir Soffer <nsof...@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)RHEL-PSseries-Configuration.pdf
>
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
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