Using Flash Caches improves the performance of a storage system.
You can configure Flash Cache and disks based on the workload requirements of a storage system. By determining the read workload (number of read operations) served by Flash Cache and disks, you can analyze the performance of the storage system.
Flash Cache does not contain any data during storage system boot or when control is returned to the storage system after a takeover event. Therefore, disks serve all the data read requests of the storage system.
The Flash Cache module is slowly populated with data when data read requests are served. Because the data read requests served by Flash Cache are faster than those served by the disks, the performance of the storage system improves.
Data read requests served by the Flash Cache module replace the data read requests served by the disks and, therefore, the performance improvement in the storage system is directly related to the disk reads that are replaced. To understand the impact of Flash Cache on storage system performance, you must view the read workload graph when the Flash Cache contains data.