From  Vinod Haval's <Inside Overview of ASM Metadata> These Views helps in understanding the following metrics
  • Physical Mapping
  • Provides Undocumented Information
  • 18 X$ Tables (May be more)
TABLE NAME DESCRIPTION
X$KFALS This table gives the details about aliases  created in ASM
X$KFCBH This is similar to x$kfbh and have same number  of rows as x$kfbh
X$KFCCE This table helps to locate the particular block
X$KFBH This table gives more physical block level info
X$KFDSK_STAT This table provides the usage metrics data which can be used for performance analysis
X$KFGRP This table provides the disk groups info in ASM
X$KFGRP_STAT This table gives the usage metrics data for all the disk groups within the ASM
X$KFGMG This table provides the details about ASM operations
TABLE NAME DESCRIPTION
X$KFKID This table provides the info about ASM disks
X$KFNCL This is similar to x$kfbh and have same number  of rows as x$kfbh
X$KFTMTA This table provides the info about DB instance  connected to ASM instance
X$KFFIL This table gives more physical block level info
X$KFFXP This table provides the physical extent allocation mapping info within ASM files
X$KFDAT
X$KFDPARTNER
X$KFCLLE