Write-through is used when the data is written to both cache and persistent storage. Useful for less intensive writes and read intensive applications.
Write-back is used when data is written to cache and a background offload will processor or application will be used to copy the data from the cache to persistent storage. IO will be acknowledged on the cache write itself. low read latency and high throughput for write intensive applications. Cache may need to be powered with an alternate source or cache to be duplicated to avoid data loss on power loss or cache failure.
Write-around is used when cache is bypassed and directly written to the persistent data. Less use of cache and most time cache miss. So higher latency.