Supermicro SuperServer SYS-1029U-TN12RV User Manual page 223

Appendix F: Configuring VROC RAID Settings
RWH Policy
Press <Enter> and the following screen will appear. If any device has been set as a journaling
drive (see pages 220 and 221), the options are Distributed PPL, Journaling Drive, and
Disable.
If no device has been set as a journaling drive, the options are Distributed PPL and Disable.
Note 1: Partial parity logging (PPL) can be defined as the result of XOR calculation of old data
and old parity. PPL is a feature available for RAID5 volumes. While a power/drive-failure/crash
occurring, PPL information helps rebuild the RAID volume and reduce the potential data loss.
Note 2: For the RWH condition, the Intel® RSTe 5.X or above RWH closure algorithm provides
the option of use of an additional NVMe device for RAID volume rebuilds (Journaling Drive
RWH closure mode). Without the use of an additional NVMe device, PPL distributed RWH
closure mode can be utilized to close the RWH by using the parity drive for example.
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