42 Chapter 2 Overview of CCI Operations
2.7.3 Data Retention Utility/Open LDEV Guard
The purpose of Data Retention Utility (DRU) (Open LDEV Guard on 9900V) is to prevent
writing to volumes by RAID storage system guarding the volume. DRU is similar to the
command that supports Database Validator, setting a protection attribute to the specified
LU.
Hiding from Inquiry command. The RAID storage system conceals the target volumes
from SCSI Inquiry command by responding “unpopulated volume” (0x7F) to the device
type.
SIZE 0 volume. The RAID storage system replies with “SIZE 0” to the target volumes
through SCSI Read capacity command.
Protection of reading. The RAID storage system protects from reading the target
volumes by responding the check condition of “Illegal function” (SenseKey = 0x05,
SenseCode = 0x2200).
Protection of writing. The RAID storage system replies with “Write Protect” in Mode
sense header, and protects from writing the target volumes by responding the check
condition of “Write Protect” (SenseKey=0x07, SenseCode=0x2700).
SVOL Disabling. The RAID storage system protects from becoming the SVOL through pair-
creation.
