Data spillage between tiers
It is possible for data to spill between the user data and metadata tiers in both directions.
Tier 1 data (user data) can spill over into Tier 0 (metadata). This only occurs if the Tier 1 file system is completely full, and additional data is written to the file system. Users are alerted if this type of spillage occurs, enabling them to better allocate data.
Tier 0 data (metadata) can also spill over into Tier 1 if necessary. Once there is space again on Tier 0, the NAS server returns the metadata to its original tier. If Tier 0 data spills over to Tier 1, performance can be degraded, including reduced write performance.
Use the fs-analyze-data-usage command to confirm data spillage.