Storage design for an HCI requires consideration of multiple factors including drive selection, volume configuration, and cache management.
Consider the following factors when selecting drives:
In an S2D setup, up to three types of drives can be used simultaneously in a pool. The fastest media is used for caching. The Ready Node for this solution provides various options for performance and sizes of drives. NVMe is the fastest available media. HDDs are the least expensive media that can be used to maximize capacity. Multi-use SSDs are in the middle of the spectrum, balancing cost and capacity.
To determine the capacity and the number of required drives, use volume sizing guidelines, approximate sizes of databases, and expected growth. Select caching media to supply the required amount of IOPS for the database.
Volumes are data stores that hold files for workloads that are running on the server. They are used to store Hyper-V files, including VHD and VHDx files. All volumes are accessible to all servers within a cluster. While configuring volumes, consider the following recommendations:
For more information about volumes and volume planning, see Planning volumes in Storage Spaces Direct on the Microsoft website.
The default settings for the write-back cache in S2D automatically size the cache based on preset factors. However, some volumes might require high IOPS. For such volumes, S2D allows a fixed amount of cache to be assigned. You can use the PowerShell parameter –WriteCacheSize in the New-Volume command for this purpose. Dell EMC recommends that you set the –WriteCacheSize parameter when you create the tempdb volume. In OLTP scenarios, you can also use this parameter to assign the volume that stores the log files.