Windows 2000 introduces a new type of disk partitioning scheme that is managed by a component called the Logical Disk Manager (LDM). Basic disks implement standard DOS-style partition tables, whereas Dynamic disks use LDM partitioning. LDM partitioning offers several advantages over DOS partitioing including replication across disks, on-disk storage of advanced volume configuration (spanned volume, mirrored volumes, striped volumes and RAID-5 volumes). My March/April two-part series on Windows NT/2000 storage management in Windows 2000 Magazine describes the details of each partitioning scheme.
Other than the Disk Management MMC-snapin and a tool called dmdiag in the Windows 2000 Resource Kit, there are no tools for investigating the internals of the LDM on-disk database that describes a system's partitioning layout. LDMDump is a utility that lets you examine exactly what is stored in a disk's copy of the system LDM database. LDMDump shows you the contents of the LDM database private header, table-of-contents, and object database (where partition, component and volume definitions are stored), and then summarizes its finding with partition table and volume listings.
Installing and Using LDMDump
To use LDMDump simply pass it the identifier of a disk.
Usage: ldmdump [- ] [-d#]
|-||Displays the supported options and the units of measurement used for output values.|
|-d#||Specifies the number of the disk for LDMDump to examine. For example, "ldmdump /d0" has LDMDump show the LDM database information stored on disk 0.|
How it Works
There are no published APIs available for obtiaining detailed information about a disk's LDM partitioning, and the LDM database format is completely undocumented. LDMDump was developed based on study of LDM database contents on a variety of different systems and under changing conditions.
For more information on the LDM on-disk structure, see:
- Inside Storage Management, Part 2, by Mark Russinovich, Windows 2000 Magazine, April 2000.
For information on how Windows NT 4.0 stores advanced volume information, see:
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