Adaptec AAR-2020SA Reference Manual page 192

The R/W Column
The R/W column displays whether the partition is read-only or
read-write. Specifically, the column can display the values listed in
Table 5-5.
Value Meaning
RO The partition is read-only.
RW The partition is read-write.
Table 5-5 R/W Array Values
disk Commands
5-21