1========================================== 2LDM - Logical Disk Manager (Dynamic Disks) 3========================================== 4 5:Author: Originally Written by FlatCap - Richard Russon <ldm@flatcap.org>. 6:Last Updated: Anton Altaparmakov on 30 March 2007 for Windows Vista. 7 8Overview 9-------- 10 11Windows 2000, XP, and Vista use a new partitioning scheme. It is a complete 12replacement for the MSDOS style partitions. It stores its information in a 131MiB journalled database at the end of the physical disk. The size of 14partitions is limited only by disk space. The maximum number of partitions is 15nearly 2000. 16 17Any partitions created under the LDM are called "Dynamic Disks". There are no 18longer any primary or extended partitions. Normal MSDOS style partitions are 19now known as Basic Disks. 20 21If you wish to use Spanned, Striped, Mirrored or RAID 5 Volumes, you must use 22Dynamic Disks. The journalling allows Windows to make changes to these 23partitions and filesystems without the need to reboot. 24 25Once the LDM driver has divided up the disk, you can use the MD driver to 26assemble any multi-partition volumes, e.g. Stripes, RAID5. 27 28To prevent legacy applications from repartitioning the disk, the LDM creates a 29dummy MSDOS partition containing one disk-sized partition. This is what is 30supported with the Linux LDM driver. 31 32A newer approach that has been implemented with Vista is to put LDM on top of a 33GPT label disk. This is not supported by the Linux LDM driver yet. 34 35 36Example 37------- 38 39Below we have a 50MiB disk, divided into seven partitions. 40 41.. note:: 42 43 The missing 1MiB at the end of the disk is where the LDM database is 44 stored. 45 46+-------++--------------+---------+-----++--------------+---------+----+ 47|Device || Offset Bytes | Sectors | MiB || Size Bytes | Sectors | MiB| 48+=======++==============+=========+=====++==============+=========+====+ 49|hda || 0 | 0 | 0 || 52428800 | 102400 | 50| 50+-------++--------------+---------+-----++--------------+---------+----+ 51|hda1 || 51380224 | 100352 | 49 || 1048576 | 2048 | 1| 52+-------++--------------+---------+-----++--------------+---------+----+ 53|hda2 || 16384 | 32 | 0 || 6979584 | 13632 | 6| 54+-------++--------------+---------+-----++--------------+---------+----+ 55|hda3 || 6995968 | 13664 | 6 || 10485760 | 20480 | 10| 56+-------++--------------+---------+-----++--------------+---------+----+ 57|hda4 || 17481728 | 34144 | 16 || 4194304 | 8192 | 4| 58+-------++--------------+---------+-----++--------------+---------+----+ 59|hda5 || 21676032 | 42336 | 20 || 5242880 | 10240 | 5| 60+-------++--------------+---------+-----++--------------+---------+----+ 61|hda6 || 26918912 | 52576 | 25 || 10485760 | 20480 | 10| 62+-------++--------------+---------+-----++--------------+---------+----+ 63|hda7 || 37404672 | 73056 | 35 || 13959168 | 27264 | 13| 64+-------++--------------+---------+-----++--------------+---------+----+ 65 66The LDM Database may not store the partitions in the order that they appear on 67disk, but the driver will sort them. 68 69When Linux boots, you will see something like:: 70 71 hda: 102400 sectors w/32KiB Cache, CHS=50/64/32 72 hda: [LDM] hda1 hda2 hda3 hda4 hda5 hda6 hda7 73 74 75Compiling LDM Support 76--------------------- 77 78To enable LDM, choose the following two options: 79 80 - "Advanced partition selection" CONFIG_PARTITION_ADVANCED 81 - "Windows Logical Disk Manager (Dynamic Disk) support" CONFIG_LDM_PARTITION 82 83If you believe the driver isn't working as it should, you can enable the extra 84debugging code. This will produce a LOT of output. The option is: 85 86 - "Windows LDM extra logging" CONFIG_LDM_DEBUG 87 88N.B. The partition code cannot be compiled as a module. 89 90As with all the partition code, if the driver doesn't see signs of its type of 91partition, it will pass control to another driver, so there is no harm in 92enabling it. 93 94If you have Dynamic Disks but don't enable the driver, then all you will see 95is a dummy MSDOS partition filling the whole disk. You won't be able to mount 96any of the volumes on the disk. 97 98 99Booting 100------- 101 102If you enable LDM support, then lilo is capable of booting from any of the 103discovered partitions. However, grub does not understand the LDM partitioning 104and cannot boot from a Dynamic Disk. 105 106 107More Documentation 108------------------ 109 110There is an Overview of the LDM together with complete Technical Documentation. 111It is available for download. 112 113 http://www.linux-ntfs.org/ 114 115If you have any LDM questions that aren't answered in the documentation, email 116me. 117 118Cheers, 119 FlatCap - Richard Russon 120 ldm@flatcap.org 121 122