Appendix E: Confi guring VROC RAID Settings
169
The feature, Mark as Journaling Drive, allows the user to set the selected NVMe device as a
journaling drive. Use the arrow keys to select Mark as Journaling Drive and press <Enter>.
The following screen will appear. The options are Yes and No.
Note: RAID Write Hole (RWH) is a condition associated with a power/drive-failure/crash
while writing to a RAID5 volume. The use of journaling drive that contains partial parity
logging (PPL) can reduce the potential data loss. Refer to the following illustration for
the use of journaling drive.
Disk1
Journaling
Drive
(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 journaling drive
(read) old data
XOR operation
(write) new data
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