Startup and Main Windows : MegaRAID Storage Manager Main Menu Window : Mirror Data Size

Mirror Data Size
Mirror data size determines the size used for storing redundant information on RAID 1 and RAID 10 virtual drives.
To view the mirror data size, in the Logical view, click the Virtual Drive node.
Mirror data size is displayed for RAID 1 and RAID 10 Volumes, as shown in the following figure.
Figure 16 Mirror Data Size
The Parity size and the Mirror data size will not be displayed for RAID 0 and RAID 00 volumes.