The only partitions that OUI displays for Windows systems are logical drives that are on disks and have been marked (or stamped) with asmtoolg or by Oracle Automatic Storage Management (Oracle ASM) Filter Driver.

If you chose not to use Oracle ASM Filter Driver (Oracle ASMFD) for configuring and marking the disks to use with Oracle ASM, then you must create disk partitions and use the asmtoolg utility to mark the disk partitions prior to installing Oracle Grid Infrastructure. You also have the option of using the asmtoolg utility during Oracle Grid Infrastructure for a cluster installation.

All disk names created by asmtoolg or asmtool begin with the prefix ORCLDISK followed by a user-defined prefix (the default is DATA), and by a disk number for identification purposes. You can use them as raw devices in the Oracle ASM instance by specifying a name \\.\ORCLDISKprefixn, where prefixn either can be DATA, or a value you supply, and where n represents the disk number.

The asmtoolg and asmtool utilities only work on partitioned disks; you cannot use Oracle ASM on unpartitioned disks. You can also use these tools to reconfigure the disks after installation. These utilities are installed automatically as part of Oracle Grid Infrastructure.

• Using asmtoolg to Mark Disks
  Use asmtoolg (GUI version) to create device names; use asmtoolg to add, change, delete, and examine the devices available for use in Oracle ASM.
• Using asmtoolg to Remove Disk Stamps
  You can use asmtoolg (GUI version) to delete disk stamps.
• asmtool Command Line Reference
  asmtool is a command-line interface for marking (or stamping) disks to be used with Oracle ASM.