Based on kernel version 2.6.25. Page generated on 2008-04-18 21:22 EST.
1 2 LDM - Logical Disk Manager (Dynamic Disks) 3 ------------------------------------------ 4 5 Originally Written by FlatCap - Richard Russon <ldm[AT]flatcap.org>[DOT] 6 Last Updated by Anton Altaparmakov on 30 March 2007 for Windows Vista. 7 8 Overview 9 -------- 10 11 Windows 2000, XP, and Vista use a new partitioning scheme. It is a complete 12 replacement for the MSDOS style partitions. It stores its information in a 13 1MiB journalled database at the end of the physical disk. The size of 14 partitions is limited only by disk space. The maximum number of partitions is 15 nearly 2000. 16 17 Any partitions created under the LDM are called "Dynamic Disks". There are no 18 longer any primary or extended partitions. Normal MSDOS style partitions are 19 now known as Basic Disks. 20 21 If you wish to use Spanned, Striped, Mirrored or RAID 5 Volumes, you must use 22 Dynamic Disks. The journalling allows Windows to make changes to these 23 partitions and filesystems without the need to reboot. 24 25 Once the LDM driver has divided up the disk, you can use the MD driver to 26 assemble any multi-partition volumes, e.g. Stripes, RAID5. 27 28 To prevent legacy applications from repartitioning the disk, the LDM creates a 29 dummy MSDOS partition containing one disk-sized partition. This is what is 30 supported with the Linux LDM driver. 31 32 A newer approach that has been implemented with Vista is to put LDM on top of a 33 GPT label disk. This is not supported by the Linux LDM driver yet. 34 35 36 Example 37 ------- 38 39 Below we have a 50MiB disk, divided into seven partitions. 40 N.B. The missing 1MiB at the end of the disk is where the LDM database is 41 stored. 42 43 Device | Offset Bytes Sectors MiB | Size Bytes Sectors MiB 44 -------+----------------------------+--------------------------- 45 hda | 0 0 0 | 52428800 102400 50 46 hda1 | 51380224 100352 49 | 1048576 2048 1 47 hda2 | 16384 32 0 | 6979584 13632 6 48 hda3 | 6995968 13664 6 | 10485760 20480 10 49 hda4 | 17481728 34144 16 | 4194304 8192 4 50 hda5 | 21676032 42336 20 | 5242880 10240 5 51 hda6 | 26918912 52576 25 | 10485760 20480 10 52 hda7 | 37404672 73056 35 | 13959168 27264 13 53 54 The LDM Database may not store the partitions in the order that they appear on 55 disk, but the driver will sort them. 56 57 When Linux boots, you will see something like: 58 59 hda: 102400 sectors w/32KiB Cache, CHS=50/64/32 60 hda: [LDM] hda1 hda2 hda3 hda4 hda5 hda6 hda7 61 62 63 Compiling LDM Support 64 --------------------- 65 66 To enable LDM, choose the following two options: 67 68 "Advanced partition selection" CONFIG_PARTITION_ADVANCED 69 "Windows Logical Disk Manager (Dynamic Disk) support" CONFIG_LDM_PARTITION 70 71 If you believe the driver isn't working as it should, you can enable the extra 72 debugging code. This will produce a LOT of output. The option is: 73 74 "Windows LDM extra logging" CONFIG_LDM_DEBUG 75 76 N.B. The partition code cannot be compiled as a module. 77 78 As with all the partition code, if the driver doesn't see signs of its type of 79 partition, it will pass control to another driver, so there is no harm in 80 enabling it. 81 82 If you have Dynamic Disks but don't enable the driver, then all you will see 83 is a dummy MSDOS partition filling the whole disk. You won't be able to mount 84 any of the volumes on the disk. 85 86 87 Booting 88 ------- 89 90 If you enable LDM support, then lilo is capable of booting from any of the 91 discovered partitions. However, grub does not understand the LDM partitioning 92 and cannot boot from a Dynamic Disk. 93 94 95 More Documentation 96 ------------------ 97 98 There is an Overview of the LDM together with complete Technical Documentation. 99 It is available for download. 100 101 http://www.linux-ntfs.org/content/view/19/37/ 102 103 If you have any LDM questions that aren't answered in the documentation, email 104 me. 105 106 Cheers, 107 FlatCap - Richard Russon 108 ldm[AT]flatcap[DOT]org
