Write-through- Write is done synchronously both to the cache and to the backing store. Write-back (or Write-behind) – Writing is done only to the cache. A modified cache block is written back to the store, just before it is replaced. Write-through（直写模式）在数据更新时，同时写入缓存Cache和后端存储。此模式的优点是操作简单；缺点是因为数据修改需要同时写入存储，数据写入速度较慢。
Write allocate (aka Fetch on write) – Datum at the missed-write location is loaded to cache, followed by a write-hit operation. In this approach, write misses are similar to read-misses. No-write allocate (aka Write-no-allocate, Write around) – Datum at the missed-write location is not loaded to cache, and is written directly to the backing store. In this approach, actually only system reads are being cached. Write allocate方式将写入位置读入缓存，然后采用write-hit（缓存命中写入）操作。写缺失操作与读缺失操作类似。
