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In addition to traditional hard disk drives (HDDs), OneFS nodes can also contain a smaller quantity of flash memory-based solid state drives (SSDs), right up to all-flash nodes. There are several ways that SSDs can be used within a cluster.
OneFS SSD Strategies are configured on a per file pool basis. These strategies include:
Any node pools consisting of off all-flash F-series nodes will automatically store all data and metadata on SSD, since those nodes do not contain any traditional hard disk drives.
The following SSD strategy decision tree explains the options available:
In all these cases, ensure that SSD capacity utilization remains below 90%.
If snapshots are enabled on a cluster, use the SSD Strategy “Use SSDs for metadata read/write acceleration” to enable faster snapshots deletes. The SSD metadata write strategy will require 6-10% of a pool’s capacity on SSD to accommodate all the metadata mirrors.
In order to configure a particular tier to be the default for both data and metadata, the default file pool policy requires the SSD strategy to be set to Use SSDs for data & metadata.
For more information about data tiering and management in OneFS, see the SmartPools white paper.