GPT disks can grow to a very large size. The number of partitions on a GPT disk is not constrained by temporary schemes such as container partitions as defined by the MBR Extended Boot Record (EBR). The GPT disk partition format is well defined and fully self-identifying. Data critical to platform operation is located in partitions and not in unpartitioned or "hidden" sectors.

The GUID Partition Table (GPT) was introduced as part of the Extensible Firmware Interface (EFI) initiative. GPT provides a more flexible mechanism for partitioning disks than the older Master Boot Record (MBR) partitioning scheme that has been common to PCs. A partition is a contiguous space of storage on a physical or logical disk that functions as though it were a physically separate disk. Partitions are visible to the system firmware and the installed operating systems.

Chapter 16 of the Extensible Firmware Interface (EFI) specification defines the GPT format. This document is available at http://developer.intel.com/ technology/ efi/ download.htm .

No. GPT disks are self-identifying. All the information needed to interpret the partitioning scheme of a GPT disk is completely contained in structures in specified locations on the physical media.

The specification allows an almost unlimited number of partitions, but the Windows implementation restricts this to 128 partitions. The number of partitions is limited by the amount of space reserved for partition entries in the GPT.

The Protective MBR protects GPT disks from previously released MBR disk tools such as Microsoft MS-DOS FDISK or Microsoft Windows NT Disk Administrator. These tools are not aware of GPT and do not know how to properly access a GPT disk. Legacy software that does not know about GPT interprets only the Protected MBR when it accesses a GPT disk.

GPT and MBR disks are managed the same way. Disks can be formatted as GPT or MBR using the Diskpart.exe command-line utility or by using the Disk Administrator snap-in. Volumes can be created on both GPT and MBR disks, and both kinds of disks can be mixed in the same dynamic disk group.

ASE and Subnet Solutions are no longer selling the GPT / Protocol Pak to new customers. Current customers of either ASE's GPT or Subnet's Protocol Pak will be fully supported under the current arrangements. For any additional requirements for GPT / Protocol Pak products, please contact the initial source code provider (ASE or Subnet Solutions).

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If this occurred, you must have used an MBR-only-aware disk tool to access the GPT disk. See answers #8 through #10, earlier.

GPT and MBR disks can be mixed on systems that support GPT, as described earlier the following restrictions apply: Systems that support EFI require that the boot partition must reside on a GPT disk. Other hard disks can be either MBR or GPT. Both MBR and GPT disks can be present in a single dynamic disk group. Volume sets can span both MBR and GPT disks. However, the MBR cylinder alignment restriction might cause some difficulties mirroring or striping MBR and GPT disks.

NTFS is recommended on all basic data partitions and all dynamic volumes. Windows Setup and the Disk Management snap-in offer only NTFS. To circumvent that, the partition or volume must be formatted explicitly via the Format command-line tool.

This product was originally developed by ASE and marketed as the GPT product. As the result of a marketing and product partnering agreement between ASE and SUBNET Solutions, the GPT has been renamed to Protocol Pak and is now being handled as a Partnered Product between the two companies.

Windows XP x64 edition can use GPT disks for data only. Only Windows for Itanium-based systems can boot from GPT partitions.

No. The 32-bit version will see only the Protective MBR. The EE partition will not be mounted or otherwise exposed to application software.

No. The Disk and Partition GUIDs will no longer be unique. This must never happen. You can make a sector-by-sector copy of the contents of ESP or basic data partitions.

Yes; however, there are some key caveats. The OEM Preinstallation Kit (OPK) initializes the Disk and Partition GUIDs to zero. On first boot of Windows, the operating system generates unique GUIDs. The OPK only supports generation of ESP, MSR, and basic data partitions. If an application has recorded any Disk or Partition GUIDs it may break.

If you are a GPT customer (purchased product directly from ASE), Please contact ASE sales for an up-to-date price list or to request a formal quotation. If you are a Protocol Pak customer (purchased product directly from Subnet Solutions), please visit the SUBNET web site at http://www.subnetsolutions.com/ and check under Products for Protocol Source Code Libraries for a description and pricing information on the Protocol Pak product or contact Subset sales.

You should first check the FAQ's and Knowledge Database for the GPT / Protocol Pak product. Answers to the most commonly asked questions and problems encountered can be found in these on-line resources. If you can not find the answer or solution on-line, you can contact technical support by e-mail, telephone, and Fax. If you are a GPT customer (purchased product directly from ASE), please contact ASE support ( support@ase-systems.com or 408-364-0500).