Read Sectors From a Disk
VixDiskLib_Read() reads a range of sectors from an open virtual disk. You specify the beginning sector and the number of sectors. Sector size could vary, but in <vixDiskLib.h> it is defined as 512 bytes.
vixError = VixDiskLib_Read(srcHandle, i, j, buf);

Write Sectors To a Disk
VixDiskLib_Write() writes one or more sectors to an open virtual disk. This function expects the fourth parameter buf to be VIXDISKLIB_SECTOR_SIZE bytes long.
vixError = VixDiskLib_Write(newDisk.Handle(), i, j, buf);