When Defer-Write is enabled and both L1 and L2 cache are configured for write caching, write requests are processed sequentially between them.
Incoming write-data is always first stored in the L1 cache. Once the allocated L1 write space is full, new incoming data will then be directed to and stored in the L2 cache.
The handling of the accumulated data in the full L1 cache depends on the advanced option "Flush L1 to L2". If this option is disabled, the data in L1 is flushed directly to the underlying hard disk. If enabled, the L1 data is transferred into the L2 cache. Once space is freed, the L1 cache resumes caching new incoming write-data.
Ultimately, whether deferred data resides in L1 or L2 cache, it will be flushed to the hard disk once the configured Defer-Write conditions are met (e.g., when the latency timer expires).