PVC in unused when loosing a node of two.

[S3LL1G28]

Hi,
I have 3 controlplanes and two workers.

I used a placement of two for replication.

If I cordon and drain a node, and then uncordon my node I have all my pvc in unused state.

an abstract:

kubectl -n piraeus exec -it deployment/linstor-controller -- linstor volume list
╭───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
┊ Node ┊ Resource ┊ StoragePool ┊ VolNr ┊ MinorNr ┊ DeviceName ┊ Allocated ┊ InUse ┊ State ┊
╞═══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════╡
┊ k8sw1.gil-yan.net ┊ pvc-1f60b906-60b4-418d-bbc6-d55c8edbd585 ┊ lvm-thin ┊ 0 ┊ 1001 ┊ /dev/drbd1001 ┊ 3.94 GiB ┊ Unused ┊ UpToDate ┊
┊ k8sw2.gil-yan.net ┊ pvc-1f60b906-60b4-418d-bbc6-d55c8edbd585 ┊ lvm-thin ┊ 0 ┊ 1001 ┊ /dev/drbd1001 ┊ 3.94 GiB ┊ Unused ┊ UpToDate ┊
┊ k8sw1.gil-yan.net ┊ pvc-430f8dc8-aca4-4b3e-8b5c-7a90bf281123 ┊ lvm-thin ┊ 0 ┊ 1007 ┊ /dev/drbd1007 ┊ 173.70 MiB ┊ Unused ┊ UpToDate ┊
┊ k8sw2.gil-yan.net ┊ pvc-430f8dc8-aca4-4b3e-8b5c-7a90bf281123 ┊ lvm-thin ┊ 0 ┊ 1007 ┊ /dev/drbd1007 ┊ 218.28 MiB ┊

kubectl -n piraeus exec -it deployment/linstor-controller -- drbdsetup status
pvc-1f60b906-60b4-418d-bbc6-d55c8edbd585 role:Secondary
disk:UpToDate
k8sw1.gil-yan.net connection:StandAlone

pvc-430f8dc8-aca4-4b3e-8b5c-7a90bf281123 role:Secondary
disk:UpToDate
k8sw1.gil-yan.net connection:StandAlone

pvc-43ab85c9-ff82-4352-821a-2139bba8ab8c role:Secondary
disk:UpToDate
k8sw1.gil-yan.net connection:StandAlone

pvc-49a29ef4-eb2e-421c-866c-12201ed245e9 role:Secondary

I'm sorry for this noob question, but how to correct this 'issue' ?

thx.

[S3LL1G28]

Just one more thing, if I delete a pod, and then it's scheduled, it can use for a time the pvc and then the controller detached the volume.

Started PV processing "pvc-5ba1ee30-a79a-4e08-be5e-f832bf25b3a1" │ │ csi-attacher I0830 08:35:24.264892 1 csi_handler.go:623] CSIHandler: processing PV "pvc-5ba1ee30-a79a-4e08-be5e-f832bf25b3a1" │ │ csi-attacher I0830 08:35:24.264896 1 util.go:106] Finalizer removed from "csi-3f18a26eb10abb70922f8ef5c5dc26f05380e055cbd3b21a4a13e524304bc068" │ │ csi-attacher I0830 08:35:24.264903 1 csi_handler.go:645] CSIHandler: processing PV "pvc-5ba1ee30-a79a-4e08-be5e-f832bf25b3a1": no deletion timestamp, ignoring │ │ csi-attacher I0830 08:35:24.264910 1 csi_handler.go:295] Fully detached "csi-3f18a26eb10abb70922f8ef5c5dc26f05380e055cbd3b21a4a13e524304bc068" │ │ csi-attacher I0830 08:35:24.264917 1 csi_handler.go:240] CSIHandler: finished processing "csi-3f18a26eb10abb70922f8ef5c5dc26f05380e055cbd3b21a4a13e524304bc068" │ │ csi-attacher I0830 08:35:24.264930 1 controller.go:210] Started VA processing "csi-3f18a26eb10abb70922f8ef5c5dc26f05380e055cbd3b21a4a13e524304bc068" │ │ csi-attacher I0830 08:35:24.264941 1 controller.go:217] VA "csi-3f18a26eb10abb70922f8ef5c5dc26f05380e055cbd3b21a4a13e524304bc068" deleted, ignoring │ │ linstor-csi time="2024-08-30T08:35:24Z" level=info msg="resource not temporary (not created by Attach) not deleting" linstorCSIComponent=client targetNode=k8sw2.gil-yan.net volume=pvc-848c5e94-13cb-4ec8-aa5a-c │ │ csi-attacher I0830 08:35:24.366769 1 connection.go:200] GRPC response: {} │ │ csi-attacher I0830 08:35:24.366861 1 connection.go:201] GRPC error: <nil> │ │ csi-attacher I0830 08:35:24.366936 1 csi_handler.go:581] Detached "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" │ │ csi-attacher I0830 08:35:24.367039 1 util.go:80] Marking as detached "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" │ │ csi-attacher I0830 08:35:24.404487 1 controller.go:261] Started PV processing "pvc-848c5e94-13cb-4ec8-aa5a-cb8789235c6c" │ │ csi-attacher I0830 08:35:24.404510 1 csi_handler.go:623] CSIHandler: processing PV "pvc-848c5e94-13cb-4ec8-aa5a-cb8789235c6c" │ │ csi-attacher I0830 08:35:24.404519 1 csi_handler.go:645] CSIHandler: processing PV "pvc-848c5e94-13cb-4ec8-aa5a-cb8789235c6c": no deletion timestamp, ignoring │ │ csi-attacher I0830 08:35:24.405196 1 util.go:106] Finalizer removed from "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" │ │ csi-attacher I0830 08:35:24.405312 1 csi_handler.go:295] Fully detached "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" │ │ csi-attacher I0830 08:35:24.405399 1 csi_handler.go:240] CSIHandler: finished processing "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" │ │ csi-attacher I0830 08:35:24.405521 1 controller.go:210] Started VA processing "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" │ │ csi-attacher I0830 08:35:24.405638 1 controller.go:217] VA "csi-6b6fa604013a2ea34f4bd414ad7ba60b1faa4bbccacce30b12cb2f5d49db3db2" deleted, ignoring │ │ linstor-csi time="2024-08-30T08:35:24Z" level=info msg="resource not temporary (not created by Attach) not deleting" linstorCSIComponent=client targetNode=k8sw2.gi

[WanzenBug]

Perhaps this is related to the HA Controller. Check the logs of the ha-controller containers to see if it tries to evict some pods.

It looks like DRBD thinks it is in a split-brain situation, indicated by the StandAlone connection. This is because you only have 2 nodes with no third "witness node". So whenever one node disconnects, both nodes will go into standalone mode.

To get out of this state, see https://linbit.com/drbd-user-guide/drbd-guide-9_0-en/#s-resolve-split-brain

And I recommend to have a third node to create a tie breaker resource. This makes splitbrains impossible.

[S3LL1G28]

Hi @WanzenBug ,

Thank you for your quick answer. I have checked my HA controller log and effectively, it's continuoulst evict pods.

Before I have three nodes but my third node is "sick". I was thinking that two nodes will be ok.

OK so I will repair it. But a last question.

If I loose my third node and if I evict one of the twqo node, so finllay only one node and then my second node come back.

Is there something I can do by command line to force pvc mounting. This is in case I loose a machine for a day and continue having pvc working.

Again thank you for your support.

[S3LL1G28]

I was thinking by recovering my third node everything will be ok. But Ha controller continue to evict.

kubectl linstor node list
╭────────────────────────────────────────────────────────────────────╮
┊ Node ┊ NodeType ┊ Addresses ┊ State ┊
╞════════════════════════════════════════════════════════════════════╡
┊ k8sw1.gil-yan.net ┊ SATELLITE ┊ 10.244.3.188:3366 (PLAIN) ┊ Online ┊
┊ k8sw2.gil-yan.net ┊ SATELLITE ┊ 10.244.4.23:3366 (PLAIN) ┊ Online ┊
┊ k8sw3.gil-yan.net ┊ SATELLITE ┊ 10.244.5.160:3366 (PLAIN) ┊ Online ┊

Connection stay in Standalone and sometimes I saw a pvc in primary and then goes secondary.

[S3LL1G28]

pvc-1f60b906-60b4-418d-bbc6-d55c8edbd585 role:Secondary
  disk:UpToDate
  k8sw1.gil-yan.net connection:StandAlone

pvc-430f8dc8-aca4-4b3e-8b5c-7a90bf281123 role:Secondary
  disk:UpToDate
  k8sw1.gil-yan.net connection:StandAlone

pvc-43ab85c9-ff82-4352-821a-2139bba8ab8c role:Secondary
  disk:UpToDate
  k8sw1.gil-yan.net connection:StandAlone

pvc-49a29ef4-eb2e-421c-866c-12201ed245e9 role:Secondary
  disk:UpToDate
  k8sw1.gil-yan.net connection:StandAlone

pvc-5ba1ee30-a79a-4e08-be5e-f832bf25b3a1 role:Secondary
  disk:UpToDate
  k8sw1.gil-yan.net connection:StandAlone

pvc-848c5e94-13cb-4ec8-aa5a-cb8789235c6c role:Secondary
  disk:UpToDate
  k8sw1.gil-yan.net connection:StandAlone

pvc-8df9269b-3378-42ec-a42d-753bba870b7d role:Primary

[WanzenBug]

Yes, because of the split brain I mentioned ealier, check https://linbit.com/drbd-user-guide/drbd-guide-9_0-en/#s-resolve-split-brain for how to get out of it.

Basically you need to decide which node has the most up-to-date data, and mark all other nodes as outdated

[S3LL1G28]

Sorry I've missed your link. I was there and try search away as I don't succeed to execute commands.

May I ask you to show an example ?

if i want to do drbdadm disconnect pvc-1f60b906-60b4-418d-bbc6-d55c8edbd585.

it tells me no resources defined!

[WanzenBug]

if i want to do drbdadm disconnect pvc-1f60b906-60b4-418d-bbc6-d55c8edbd585.

You need to connect to the linstor-satellite.... pod and execute those commands there.

[S3LL1G28]

Again sorry for my "noobery".

It's ok, I've got all my pvc running.

To summup for others persons. You have to determinate which node is the primary for the ressource . attribute the primary role and then go on other nodes and follow instructions from the url you give to me.

After that everything is ok

A big thank you.

[S3LL1G28]

A last thing I don't realize. Having only 2 replications is a bad thing for three nodes.

so it's better to have 3 replications. But it will cost three times the disk space no ?