Figure 2.34 Horcm And Command Issue Process; Figure 2.35 Flow Of Command Issue - Hitachi TAGMASTORE MK-90RD011-25 User Manual

2.8.7.1 Command Competition
The CCI commands are asynchronous commands issued via the SCSI interface. Accordingly, if
several processes issue these commands to a single LDEV, the storage system cannot take
the proper action. To avoid such a problem, two or more WR commands should not be issued
to a single LDEV. The command initiators should not issue two or more WR commands to a
single LDEV unless the storage system can receive commands with independent initiator
number * LDEV number simultaneously.
Command
process
Command
process
Command
process

Figure 2.34 HORCM and Command Issue Process

2.8.7.2 Flow of Commands
Figure 2.35 shows the flow of RD/WR command control in a specified LBA#.
Host side
Write()
Read()

Figure 2.35 Flow of Command Issue

66 Chapter 2 Overview of CCI Operations
RD/WR command
HORCM
(CCI)
LDEV (Target#, LUN#)
Command area
Scanning edit data by reading
Hitachi RAID
(Command device)
Hitachi RAID side
Write/read
processing code
Input data
Input parameter
Edited data