Trident is in an early stage of development, and thus, there are several outstanding issues to be aware of when using it:
- Due to known issues in Kubernetes 1.5 (or OpenShift 3.5) and earlier, use of iSCSI with ONTAP or E-Series in production deployments is not recommended. See Kubernetes issues #40941, #41041 and #39202. ONTAP NAS and SolidFire are unaffected. These issues are fixed in Kubernetes 1.6 (and OpenShift 3.6).
- Although we provide a deployment for Trident, it should never be scaled beyond a single replica. Similarly, only one instance of Trident should be run per Kubernetes cluster. Trident cannot communicate with other instances and cannot discover other volumes that they have created, which will lead to unexpected and incorrect behavior if more than one instance runs within a cluster.
- Volumes and storage classes created in the REST API will not have
corresponding objects (PVCs or
StorageClasses) created in Kubernetes; however, storage classes created via
tridentctlor the REST API will be usable by PVCs created in Kubernetes.
- If Trident-based
StorageClassobjects are deleted from Kubernetes while Trident is offline, Trident will not remove the corresponding storage classes from its database when it comes back online. Any such storage classes must be deleted manually using
tridentctlor the REST API.
- If a user deletes a PV provisioned by Trident before deleting the
corresponding PVC, Trident will not automatically delete the backing volume.
In this case, the user must remove the volume manually via
tridentctlor the REST API.
- Trident will not boot unless it can successfully communicate with an etcd instance. If it loses communication with etcd during the bootstrap process, it will halt; communication must be restored before Trident will come online. Once fully booted, however, Trident is resilient to etcd outages.
- When using a backend across multiple Trident instances, it is recommended
that each backend configuration file specify a different
storagePrefixvalue for ONTAP backends or use a different
TenantNamefor SolidFire backends. Trident cannot detect volumes that other instances of Trident have created, and attempting to create an existing volume on either ONTAP or SolidFire backends succeeds as Trident treats volume creation as an idempotent operation. Thus, if the
TenantNamedoes not differ, there is a very slim chance to have name collisions for volumes created on the same backend.
- Due to a known issue in the containerized version of OpenShift, where some iSCSI initiator utilities are missing, Trident will fail to install of configure iSCSI storage systems. This only affects OpenShift Origin. See OpenShift issues #18880.
- ONTAP cannot concurrently provision more than one FlexGroup at a time unless the set of aggregates are unique to each provisioning request.