In a traditional three-tier architecture, application and database administrators often work with storage administrators to create a custom storage design to suit their environment, which includes designating the RAID level and block size for different types of files, such as database tablespaces or log files. This process can become cumbersome to manage, especially if there are multiple databases. Nutanix eliminates the problems associated with choosing the optimal RAID and block size. Once you create a VG with the required number of vDisks for your database or application, you’re ready to deploy. The following table outlines the recommended minimum disk layout for a database such as Oracle. For other workloads please refer to the specific application’s best practices guide.
There are two ways to create vDisks on Nutanix for your VMs:
Nutanix native vDisks.
Nutanix volume groups.
Nutanix Native vDisks
The Nutanix native vDisk option simplifies VM administration because it doesn’t require Nutanix VGs. When you create a VM using Prism, add more vDisks to the VM for the application or database the same way you add a vDisk to the VM for the boot disk. If you have an application or database that doesn’t have intensive I/O requirements, native vDisks are the best option.
Nutanix Volume Groups
Alternatively, you can attach Nutanix VGs, which are collections of vDisks, to the VMs. VGs enable you to separate the data vDisks from the VM’s boot vDisk. This separation allows you to create a protection domain that consists only of the data vDisks for snapshots and cloning. In addition, VGs let you configure a cluster with shared-disk access across multiple VMs. Supported clustering applications include Oracle Real Application Cluster (RAC), IBM Spectrum Scale (formerly known as GPFS), Veritas InfoScale, and Red Hat Clustering. To attach the VG to multiple VMs when you use the aCLI, create it with a shared=true attribute. If you use Prism, answer yes when you attach the VG to a second VM. There are two ways to use Nutanix VGs: default VG and VGLB.
Default Volume Group
This type of VG provides the best data locality because it doesn’t load-balance vDisks in a Nutanix cluster, which means all vDisks in default VGs have a single CVM providing their I/O. For example, in a four-node Nutanix cluster that includes a VG with eight vDisks attached to a VM, a single CVM owns all the vDisks and all I/O to the eight vDisks goes through this CVM.