I’m seeing the same issue. I’m not familiar with where to access the “Prometheus UI”. Can you point me to some instructions on how to do this and I’ll gladly collect the output of that command.
FWIW, here are the interfaces on my machine:
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp6s0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond0 state UP group default qlen 1000
link/ether 58:97:bd:8f:76:d8 brd ff:ff:ff:ff:ff:ff
3: enp7s0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond0 state UP group default qlen 1000
link/ether 58:97:bd:8f:76:d8 brd ff:ff:ff:ff:ff:ff
4: enp17s0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond1 state UP group default qlen 1000
link/ether 5c:83:8f:80:13:a4 brd ff:ff:ff:ff:ff:ff
5: enp18s0: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 9000 qdisc mq master bond1 state UP group default qlen 1000
link/ether 5c:83:8f:80:13:a4 brd ff:ff:ff:ff:ff:ff
6: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether ec:bd:1d:08:87:8e brd ff:ff:ff:ff:ff:ff
7: eno2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
link/ether ec:bd:1d:08:87:8f brd ff:ff:ff:ff:ff:ff
8: bond1: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP group default qlen 1000
link/ether 5c:83:8f:80:13:a4 brd ff:ff:ff:ff:ff:ff
inet 10.9.192.196/24 brd 10.9.192.255 scope global noprefixroute bond1
valid_lft forever preferred_lft forever
inet6 fe80::5e83:8fff:fe80:13a4/64 scope link noprefixroute
valid_lft forever preferred_lft forever
9: bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP group default qlen 1000
link/ether 58:97:bd:8f:76:d8 brd ff:ff:ff:ff:ff:ff
inet 10.122.242.196/24 brd 10.122.242.255 scope global noprefixroute bond0
valid_lft forever preferred_lft forever
inet6 fe80::5a97:bdff:fe8f:76d8/64 scope link noprefixroute
valid_lft forever preferred_lft forever
10: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:d2:19:1a:28 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
valid_lft forever preferred_lft forever
I did notice that docker0 has an MTU of 1500 as do the eno1 and eno2 interfaces which I’m not using. I’m not sure if that’s related to the error. I’ve been meaning to try changing the MTU on the eno interfaces just to see if that makes a difference but haven’t gotten around to it.
-Paul
> On Aug 4, 2021, at 2:31 PM, Ernesto Puerta <epuertat@xxxxxxxxxx> wrote:
>
> Hi J-P,
>
> Could you please go to the Prometheus UI and share the output of the
> following query "node_network_mtu_bytes"? That'd be useful to understand
> the issue. If you can open a tracker issue here:
> https://tracker.ceph.com/projects/dashboard/issues/new ?
>
> In the meantime you should be able to mute the alert (Cluster > Monitoring
>> Silences).
>
> Kind Regards,
> Ernesto
>
>
> On Wed, Aug 4, 2021 at 5:49 PM J-P Methot <jp.methot@xxxxxxxxxxxxxxxxx>
> wrote:
>
>> Hi,
>>
>> We're running Ceph 16.2.5 Pacific and, in the ceph dashboard, we keep
>> getting a MTU mismatch alert. However, all our hosts have the same
>> network configuration:
>>
>> => bond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 9000 qdisc
>> noqueue state UPgroup default qlen 1000 => vlan.24@bond0:
>> <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UPgroup
>> default qlen 1000
>>
>>
>> Physical interfaces, bond andvlans are all setto9000.
>>
>> The alert's message looks like this :
>>
>> Node node20 has a different MTU size (9000) than the median value on
>> device vlan.24.
>>
>> Is this a known Pacific bug? None of our other Ceph clusters does this
>> (they are running on Octopus/Nautilus).
>>
>> --
>>
>> Jean-Philippe Méthot
>> Senior Openstack system administrator
>> Administrateur système Openstack sénior
>> PlanetHoster inc.
>>
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>>
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