Users Guide

Storage tiers

Storage tiers enable the mixing of HDDs and SSDs in one pool and take advantage of the faster SSDs to

maximize IOPS and throughput by using the SSDs as cache. Storage Spaces constantly analyzes data

usage patterns and moves the most frequently used data from the HDD tier to the SSD tier to speed up

access.

NOTE: Storage tiers are only supported with mirroring or simple spaces.

Storage Spaces creates a heat map based on the frequency that the data is used. Once in a day, an

optimization process automatically runs and the most frequently accessed data (hot data) is moved to the

SSD tier and less frequently accessed data (cold data) is moved to the HDD tier.

Because the data on the SSD tier is only updated once in a day (by default), if required, you can manually

optimize data by running the following PowerShell command.

defrag.exe /C /H /K /G

You must run this command on all storage nodes in the cluster, because it only optimizes the VDs owned

by the storage node where the command was run.

When validating the performance of your solution, ensure to perform benchmarks over the course of

several days to allow the SSD tier to optimize for your workload, or you can manually optimize the SSD

tier. Manually optimizing storage tier data by using the command above generates a Storage Tier

Optimization Report. The Storage Tier Optimization report provides data on the storage tier, which can

be used to identify methods to optimize performance.

You may want the ability to permanently place a frequently used file on the SSD tier, for example, a

frequently accessed VHDX file that requires low latency and high throughput. You can accomplish this by

pinning files to the SSD tier.

Consider the following before running the command:

• You must run the command from the storage node which owns the CSV where the file is stored.

• You must use the local path of the CSV on the storage node.

Even after pinning the file, it will not move to the SSD tier until the next optimization (or if you run it

manually).

Dell recommends you to use pin sparingly, because the primary goal of storage tiers is to allow the heat

map process to optimize the tiers.

Run the following Powershell command to pin files to the SSD tier.

Set-FileStorageTier –FilePath <localFilePath> -DesiredStorageTierFriendlyName

Run the following Powershell command to unpin files from the SSD tier.

Set-FileStorageTier –FilePath <localFilePath>

Run the following PowerShell command to review all files currently pinned.