ARCHITECTURE – VXRAIL VS. VSA

Hyperconverged storage solutions require the installation of a virtual storage appliance on each host. However, in the case of VSAN, because it is embedded in the ESXi kernel, all the Virtual SAN intelligence are already built in to the hypervisor and there are no additional components to install.

Because it is embedded in the hypervisor VSAN provides the shortest path for I/O, making storage operations optimally efficient and does not consume CPU resources unnecessarily. Even during maintenance operations and VM migrations, storage operations are seamlessly handled.

VxRail VSAN provides the software defined storage layer. There are several benefits to VSAN but the primary 2 main reasons VSAN is ideal for a hyper-converged infrastructure appliance are as follows:

1.Kernel Integration – The software controlling the storage is integrated into the hypervisor. Why is this so important? The alternative to kernel integration is using a Virtual Storage Appliance (VSA) where the storage system must run separately as a guest virtual machine (VM) on top of the hypervisor as opposed to being a part of it. The issue with these types of implementations is that the VSA VMs content with resources against the workloads being supported. The VSA requires a lot of tuning and balancing to get it optimized to off-set I/O contention such that workloads can perform optimally which requires expertise and can be time consuming and a challenging exercise

2.Storage Based Policy Management (SBPM) – When making a decision to deploy a software defined data center (SDDC) approach it is very important that any platform you consider have the capability of enforcing top down policies between the various virtual layers (compute, storage, network) and provide control over the service objectives in all of these layers. VSAN enables the setting of storage policies at the kernel layer with seamless integration higher up in the management and orchestration layer such as with the vRealize Suite or those provided via 3rd party tools so that when services are rendered all of the associated services and their attributes cascade throughout the infrastructure. SBPB provides top to bottom control of how the workloads perform in the appliance.

• Technical advantages: VSAN code is in the vSphere kernel
• No need to install Virtual Storage Appliances (VSA)
• CPU utilization <10%
• No reserved memory required
• Provides the shortest path for I/O
• Seamlessly handles VM migrations
• Operational advantages: VSAN is built with and for vSphere Storage Policy Based Management
• No new management console
• No planning out or carving up disk pools
• Virtual SAN self-tunes to keep policy compliance

VSAN is integrated into Kernel of vSphere

• More efficient and performant than a Virtual Storage Appliance

Storage Policy Based Management

• Storage policies are directly embedded onto storage object
• Data protection, Performance/QoS, Data Reduction
• Policies follow your virtual machine
• Seamlessly integrated with vRealize

VxRail Appliance software is customer upgradeable via a fully automated and validated process as of VxRail 4.0 software. The software upgrade is initiated via download from VxRail Manager, and it automatically downloads all software ready to be updated including VxRail Manager VM, vCenter Server and PSC, ESXi hosts, and ESRS. The automated process consists of four steps including download of the VxRail software, a readiness check, the actual update of the software, and finally, validation and upgrade post checks. The final validation step ensures the upgrade was successful, and the VxRail Appliance is fully functional at the new, upgraded version of software. Below diagram shows the four automated steps of a customer executed VxRail Appliance software upgrade. Step 3 is performed one node at a time, where the ESXi host is placed in maintenance mode, and using vMotion, the VMs are moved to other nodes making the upgrade process non-disruptive. To do this automatically vSphere Enterprise Edition Plus is required. If the VxRail appliance is not currently running VxRail 3.5 or using vSphere Standard Edition license, services are required to perform the upgrade. (It is best to verify with Dell EMC services that an environment meets the requirements prior to an upgrade.)

Each VxRail are included the following features,

• VMware vSphere Replication
• Dell EMC RecoverPoint for Virtual Machines
• Integrated Backup and Recovery with vSphere Data Protection (VDP)
• VMware Stretched Cluster