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Appendix B: Standardized Warning Statements
The item, Mark as Journal Disk, allows the user to set the selected NVMe device as a journal
disk. Use the arrow keys to select Mark as Journal Disk and press <Enter>. The following
screen will appear. Options are
Yes
and No.
Note:
RAID Write Hole (RWH) is a condition associated with a power/drive-failure/
crash while writing RAID5 strips. The use of journal disk that contains partial parity
logging (PPL) can reduce the potential data loss. Refer to the following illustration for
the use of journal disk.
Disk1
Journal
Disk
(Data)
Disk2
(Data)
Disk3
(Data)
Disk4
(Parity)
RAID SW for Read-modify-write Case
(PPL)
Partial parity logging (PPL) = old data XOR old parity
New parity = new data XOR PPL
(read) old parity
XOR operation
(write) new parity
Store PPL to the journal disk
(read) old data
XOR operation
(write) new data