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Storage plays an essential role in the KVM implementation The storage dictates the type of cluster: shared or local. Shared storage is the more common KVM cluster, enabling features such as HA and migration. During the oVirt Engine installation outlined in this paper, an initial shared storage domain was required and created on PowerFlex. Dell Technologies recommends creating additional storage domains on PowerFlex for objects such as VMs and ISOs either on FC (SDC) or NFS. The process for doing so follows next.
When creating new shared storage domains in a KVM environment, the user is limited to certain storage types. They are the following and appear in Figure 39:
Putting aside GlusterFS, PowerFlex supports two of these protocols, NFS and Fibre Channel (FC). While PowerFlex has native NFS support, it does not have FC support. Technically, however, oVirt is simply looking for SCSI devices, so despite PowerFlex presenting volumes over the IP network, if the KVM host is configured properly, OVM finds PowerFlex volumes that are mapped to the hosts through the Storage Data Client, or SDC. These volumes are regular SCSI devices, just like those presented with iSCSI or FC. KVM thus treats PowerFlex devices that SDS presents as legitimate storage for the shared storage domain.
KVM has specific requirements for each storage type that is used in a storage domain. The next sections cover the types that are supported with PowerFlex.
Network File System (NFS) is a distributed file system protocol that allows users to access files over a network. NFS is a common choice for storage domains because it is simple to implement and manage. When using NFS storage with KVM, it is important to pick a platform that meets the performance and scalability requirements of your workloads. PowerFlex is the perfect solution for KVM as its NAS implementation can scale up to 16 nodes, supports both NFS 3 and 4.1, and delivers superior performance when matched with a high performance, low latency network.
For NFS, the permissions and the ownership of the share must be altered so that the oVirt Engine can use it. The available ownership and permissions on the PowerFlex NFS export are limited and do not meet the requirements of KVM. It is necessary, therefore, to manipulate the share either on an existing KVM node, or on a separate host altogether. In the following example, a Linux host was configured for the sole purpose of meeting the prerequisites of NFS storage. This example sets up the storage for the self-hosted oVirt Engine. It is the same process as is required for creating an NFS storage domain after the oVirt Engine deployment completes. The procedure to create the NFS and make it available to the KVM node is as follows.