On Mon, Feb 1, 2021 at 4:47 PM Gianluca Cecchi
<gianluca.cec...@gmail.com> 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
>
>
>>
>>
>> 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?
Yes. Working on configurable sanlock io timeout revealed that these values
should match.
> 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?
Yes.
The easiest way to get vdsm defaults is to change the the file to use
an older version,
(e.g. use 1.9), remove the private comment, and run:
vdms-tool configure --force --module multipath
Vdsm will upgrade your old file to the most recent version, and backup
your old file
to /etc/multipath.conf.timestamp.
> On my system with vdsm-python-4.40.40-1.el8.noarch I have this inside that
> file
> _NO_PATH_RETRY = 16
Yes, this matches sanlock default io timeout (10 seconds).
>> 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.
For 120 seconds, you likey need
sanlock:io_timeout=20
no_path_retry=32
Because of the different way sanlock and multipath handles timeouts.
Also note that our QE never tested changing these settings, but your
feedback on this new
configuration is very important.
...
> 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
multipath -r deleages the command to multipathd daemon, this is
probably the reason
you don't see the logs here.
I think this will be more useful:
multipathd reconfigure -v3
I'm not sure about the -v3, check multipathd manual for the details.
Nir
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