This alert has been deprecated; it does not indicate a genuine issue. If triggered, it may be safely ignored and silenced.
When running VMs using ODF storage with ‘rbd’ mounter or ‘rbd.csi.ceph.com’ provisioner, Windows VMs may cause reports of bad crc/signature errors due to certain I/O patterns. Cluster performance can be severely degraded if the number of re-transmissions due to crc errors causes network saturation. ‘krbd:rxbounce’ should be configured for the VM storage class to prevent these crc errors, the “ocs-storagecluster-ceph-rbd-virtualization” storage class uses this option by default, if available.
Cluster may report a huge number of CRC errors and the cluster might experience major service outages.
Obtain a list of VirtualMachines with an incorrectly configured storage class by running the following PromQL query:
$ kubevirt_ssp_vm_rbd_volume{rxbounce_enabled="false", volume_mode="Block"} == 1
kubevirt_ssp_vm_rbd_volume{name="testvmi-gwgdqp22k7", namespace="test_ns", pv_name="testvmi-gwgdqp22k7", rxbounce_enabled="false", volume_mode="Block"} 1
The output displays a list of VirtualMachines that use a storage class without
rxbounce_enabled.
Obtain the storage class name by running the following command:
$ kubectl get pv ${PV_NAME} -o=jsonpath='{.spec.storageClassName}'
It is recommended to create a dedicated StorageClass with “krbd:rxbounce” map option for the disks of virtual machines, to use a bounce buffer when receiving data. The default behavior is to read directly into the destination buffer. A bounce buffer is required if the stability of the destination buffer cannot be guaranteed.
Note that changing the used storage class will not have any impact on existing PVCs/VMs, meaning that new VMs will be provisioned with the optimized settings but existing VMs need to be transitioned or the alert will continue to fire for those.
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: vm-sc
parameters:
# ...
mounter: rbd
mapOptions: "krbd:rxbounce"
provisioner: openshift-storage.rbd.csi.ceph.com
# ...
If you cannot resolve the issue, see the following resources: