Product manual

CDA 7 Input/Output Operations
77 A1 69UP Rev00 3-13
3.2.3.1 Fast Write
In a fast write operation, the channel director stores the data in cache and sends a
channel end and device end (or a SCSI "good ending" status) to the host computer.
The disk director then asynchronously "destages" the data from cache to the disk
device.
CONNECT TIME
OVERHEAD
TOTAL SERVICE TIME
Figure 3-11. Fast Write
Since CDA 7 writes the data directly to cache and not to disk, there are no
mechanical delays due to seek, latency, and RPS miss.