Hello, and thank you. DASD stands for Disk Array Subsystem, as I said it is old information technology..
THE CONTEXT IS: The Write Assist Device used in (...) high-availability models has been replaced with the 1MB write cache to more efficiently manage the write penalty.
write penalty [Storage System] Low apparent application write performance to RAID arrays’ virtual disks. The write penalty is inherent in RAID data protection techniques, which require multiple disk I/O requests for each application write request, and ranges from minimal (mirrored arrays) to substantial (RAID Levels 5 and 6). Many RAID array designs include features such as write-back cache specifically to minimize the write penalty.
The other entry is a blog entry found at: archives.devshed.com/forums/research-131/ It may be a good idea for you to read the context.