Preparing the Cluster
In the context of the Mayastor application, a "Mayastor Node" (MSN) is a Kubernetes worker node on which is scheduled an instance of a Mayastor data plane pod and which is thus capable of hosting storage "pools" and exporting Persistent Volumes (PV) to application pods within the cluster. A MSN makes use of block storage device(s) attached to it to contribute storage capacity to its pool(s), which supply backing storage for the Persistent Volumes dynamically-provisioned on the cluster by Mayastor.
New MSN nodes can be provisioned within the cluster at any time after the initial deployment, as aggregate demands for capacity, performance and availability levels increase.
2MiB-sized Huge Pages must be supported and enabled on a MSN. A minimum number of 1024 such pages (i.e. 2GiB total) must be available exclusively to the Mayastor pod on each node, which should be verified thus:
grep HugePages /proc/meminfo
AnonHugePages: 0 kB
ShmemHugePages: 0 kB
If fewer than 1024 pages are available then the page count should be reconfigured on the worker node as required, accounting for any other workloads which may be scheduled on the same node and which also require them. For example:
echo 1024 | sudo tee /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
This change should also be made persistent across reboots by adding the required value to the file
echo vm.nr_hugepages = 1024 | sudo tee -a /etc/sysctl.conf
All worker nodes which will have Mayastor pods running on them must be labelled with the OpenEBS engine type "mayastor". This label will be used as a node selector by the Mayastor Daemonset, which is deployed as a part of the Mayastor data plane components installation. To add this label to a node, execute:
kubectl label node <node_name> openebs.io/engine=mayastor