This page provides details about how to plan your FlexCache volumes.
When planning your FlexCache volume, consider the following guidelines for capacity, performance, and network impact:
Cache volume capacity
For maximum performance, we recommend a FlexCache volume size that is between 15% and 50% of the origin volume's size. Performance might degrade if the cache-to-origin size ratio exceeds 50%.
Cache volume performance
For FlexCache volume in Premium and Extreme service level storage pools, its performance is determined by its size and service level.
The maximum throughput calculation by service level:
Premium service level: Volume capacity (GiB) x 64 KiBps
Extreme service level: Volume capacity (GiB) x 128 KiBps
If the FlexCache volume receives too little performance due to its size, you can use the Manual QoS feature to reassign performance from other volumes in the same pool to the FlexCache volume.
For example, to achieve a throughput of 500 MiBps, you need to provision either 7.8 TiB of Premium volume or 3.9 TiB of Extreme volume.
For FlexCache volumes in Flex Unified pools, the volumes share the pool's performance with all other volumes in the pool. You can assign more throughput and IOPS to the pool as needed.
Network performance
The network performance is determined by the following factors:
Cache read hits: these are served quickly with low latency directly from the cache volume.
Cache misses: the data must be retrieved from the origin. Their performance depends on the throughput and latency of the network between the cache and origin volumes. Consider prefetching data to improve performance for resource-intensive compute jobs.
Writes: all write operations are directed to the origin. Their throughput and latency depend on the network connection between the cache and origin.