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