Hitachi HF-W100E, Instruction Manual

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4. PRECAUTIONS REGARDING THE OS
4-3
4.1.2 Embedded Enabling Features overview and examples
(1) Enhanced Write Filter with HORM (EWF)
EWF suppresses writing to storage and redirects writes to RAM's overlay cache. As a result,
the ability to manage and protect the storage of the corresponding partition on a sector units.
With the above, Writing is discarded by shutting down or restarting the OS, so it is possible to
restore to the state before EWF was enabled.
There are two types of operation modes (RAM mode / RAM registry mode) in EWF, and
the management method of EWF configuration information is different as shown below.
The EWF of this equipment operates in RAM registry mode.
● RAM mode
Manage the EWF configuration information with a partition dedicated to EWF.
● RAM registry mode (Operation mode in this equipment. It can not switch to RAM mode.)
Manage the EWF configuration information in the registry.
※
The disable option of the “ewfmgr” command can not be used
(since the contents of the setting change written in the registry are discarded by EWF).
For details of the command, see <Setting Command>.
Writing is recorded in memory, and
reading of that data is also done from
memory.
Memory
File System (FAT/NTFS)
Write filter (EWF)
Reading Writing
Storage
Partition A
OS area
Partition B
EWF configuration
information
Storage
RAM
EWF
overlay
System
Reserved
Partition A
OS area
EWF configuration
information in the
registry
Storage
RAM
EWF
overlay
System
Reserved