Temporarily Tuning LINSTOR Resource Resynchronization

There might be a situation where you need to temporarily speed up the resynchronization of a single resource in LINSTOR®. The example below is from a Kubernetes environment, but the same steps can be applied to any LINSTOR cluster.

The following steps show tuning the resynchronization rate for a LINSTOR resources in Kubernetes, pvc-78df9b41-3064-4666-b828-679779397c4b, You will likely want to repeat the steps on all LINSTOR pods where there is a replica present for the resource. You might however start with the node that is the SyncTarget.

Connect to the LINSTOR satellite pod (ns-node pod) of the SyncTarget, by entering the following command:
```
# kubectl exec -it linstor-op-ns-node-44p64 -- /bin/sh
```
Once inside the LINSTOR satellite pod, check the current setting by entering drbdsetup show. You can use this afterwards to also verify the changes.
```
# drbdsetup show pvc-78df9b41-3064-4666-b828-679779397c4b --show-default
```
Change the max-buffers value. A starting value could be 20k, but good results have also been observed with anything between 20k-80k.
```
# drbdadm net-options pvc-78df9b41-3064-4666-b828-679779397c4b --max-buffers=20k
```

Change the c-fill-target to 1M.

drbdadm peer-device-options pvc-78df9b41-3064-4666-b828-679779397c4b --c-fill-target=1M

Connect to the satellite pod of the other peers and repeat the above steps as needed.

These setting are temporary, and will be cleared if the resource is ever down-ed or up-ed, or if the node is restarted. This should help to increase the resynchronization speeds if there is available disk and network throughput. Once the synchronization is complete, you can revert to default settings by entering the following command:

# drbdadm adjust pvc-78df9b41-3064-4666-b828-679779397c4b

Again, you will want to run this on all nodes where the resource is present.