This message was deleted.

My ideal setup would place active replica on same node as pod,

The Longhorn data locality feature can achieve this

and replicas in other nodes in same az. To avoid inter-region replication traffic. Is this possible ?

Unfortunately, no Longhorn actually try to separate replicas onto different AZ to increase the availability cc @famous-shampoo-18483 @billowy-painting-56466

Thks @famous-journalist-11332 I saw a reference to region https://longhorn.io/docs/1.4.0/volumes-and-nodes/scheduling/#notice, and

<http://topology.kubernetes.io/region=|topology.kubernetes.io/region=><Region name

Id like to have some clarification. How does the region play with this availability placement ?

Region a bigger object than AZ. Region contains AZ. AZ contains nodes. Longhorn attempts to spread the replicas of volume between different regions, then different AZs, then different nodes

IIUC, cross-AZ replication should be fine. But no one would distribute replicas in different regions, since the network latency among different region (> 1ms) would greatly hurt the volume performance and make it impractical.

Agreed cross region replicas should be in control of end user, if needed. I understand longhorn 1.4.0 will try to schedule on different regions by default. Is there a way to avoid this ? disk-level tags maybe ?

YES. You group nodes by tags then use the corresponding selector for replica scheduling. This is an pretty old but powerful feature. IIRC there is no special feature for the region-level scheduling in v1.4.0...