How does the NetApp file system WAFL utilize NVRAM?

The answer is correct because NVRAM (Non-Volatile Random Access Memory) in the context of the NetApp Write Anywhere File Layout (WAFL) plays a crucial role in ensuring the durability and integrity of write operations. By utilizing NVRAM, NetApp systems can acknowledge write operations immediately to the host, creating the appearance of high performance and responsiveness. This is achieved because NVRAM provides fast write access; data is first written to NVRAM before being flushed to disk. This technique minimizes the potential for data loss in the event of a power failure, as the data in NVRAM can be retained until it is safely written to a permanent storage medium.

This approach enhances the system's performance while maintaining data integrity, as all changes can be reliably persisted without waiting for the slower disk writes to complete. Thus, the systematic use of NVRAM allows for enhanced write performance and ensures that subsequent reads can access the most recent data changes without delays.