Datastore Migrations in vCloud Director – Part 1 of 3: Introduction

Due to its length the article has been split into three parts:

Part 1: Introduction
Part 2: Individual Datastores
Part 3: Datastore Clusters

In cloud environments the end-user is completely abstracted from the actual physical hardware which hosts cloud workloads. Therefore it is expected that any hardware replacement due to its lifecycle will have minimal impact on the workloads. I have already written an article how to non-disruptively migrate the compute part – virtual datacenter from old servers to new ones: vCloud Director: Online Migration of Virtual Data Center. This series of articles talks about storage migration.

Although there is a KB article 2058094 about the subject it is not comprehensive and some important considerations are not mentioned.

When a datastore or multiple datastores are decommissioned, vApp virtual machines, catalog vApps, catalog media and vShield Edges must be migrated away. The process depends if we are migrating to a new storage profile or not, if we use fast provisioning or storage clusters.

vCloud Director 5.x consumes vSphere datastores through storage profiles which are assigned to Provider VDCs. Individual datastores cannot be added or removed from a Provider VDC directly. vCloud Director placement engine is choosing datastores for placement based on the storage profile and host connectivity. If datastore cluster with Storage DRS is used then vCloud Director placement engine relies on Storage DRS placement recommendations. Datastore cluster must have all datastore with the same Storage Capability and it is not possible to mix NFS with block based datastores. It is not possible to manage individual datastores of a datastore cluster in vCloud Director – meaning disabling them, setting disk space thresholds or enabling VAAI for fast provisioning. Those settings now apply to the whole datastore cluster. Speaking of fast provisioning, Storage vMotion of a linked clone produces full clone, storage vMotion of VAAI accelerated linked clone (hardware snapshot) is not possible (as of vSphere 5.1).

Understanding these facts it should be now easier to derive the right migration steps.

In the next article I will talk how to non-disruptively  migrate vCloud Director infrastructures from storage that is presented as individual datastores. The last article will talk about usage of datastore clusters and Storage DRS with vCloud Director.

Go to Part 2.


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