LVM a /dev/dm-X

[rga]

Hraji a učím se tu na jednom zatím nepoužívaném serveru...
Debian 5.0

Dnes jsem server pustil, něco se chtěl podívat, zkusil
fdisk -l
a překvapily mě nějaké stížnosti na /dev/dm-X, které se až do teď neobjevovaly:

# fdisk -l

Disk /dev/sda: 249.3 GB, 249376538624 bytes
255 heads, 63 sectors/track, 30318 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000080

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1          10       80293+  de  Dell Utility
/dev/sda2   *          11          73      506047+  83  Linux
/dev/sda3              74        2019    15631245   83  Linux
/dev/sda4            2020       30318   227311717+   5  Extended
/dev/sda5            2020        2263     1959898+  82  Linux swap / Solaris
/dev/sda6            2264       30318   225351756   8e  Linux LVM

Disk /dev/dm-0: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-0 doesn't contain a valid partition table

Disk /dev/dm-1: 17.1 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-1 doesn't contain a valid partition table

Disk /dev/dm-2: 154.6 GB, 154618822656 bytes
255 heads, 63 sectors/track, 18798 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-2 doesn't contain a valid partition table

Disk /dev/dm-3: 17.1 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-3 doesn't contain a valid partition table

# pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda6
  VG Name               vlm1
  PV Size               214.91 GB / not usable 2.07 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              55017
  Free PE               8937
  Allocated PE          46080
  PV UUID               v7I3nG-aRJZ-kUgd-XvwS-wm4h-ZrxX-ZSe0ae

# vgdisplay
  --- Volume group ---
  VG Name               vlm1
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                4
  Open LV               4
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               214.91 GB
  PE Size               4.00 MB
  Total PE              55017
  Alloc PE / Size       46080 / 180.00 GB
  Free  PE / Size       8937 / 34.91 GB
  VG UUID               I5SE3e-ecjI-FXby-Uebf-6CyR-Fq0t-uwo9xC

# lvdisplay
  --- Logical volume ---
  LV Name                /dev/vlm1/tmp
  VG Name                vlm1
  LV UUID                j3o0T0-aiSM-ZMuB-YoWI-vvVx-4h2h-JnExHE
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                4.00 GB
  Current LE             1024
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:0

  --- Logical volume ---
  LV Name                /dev/vlm1/var
  VG Name                vlm1
  LV UUID                gCsIiD-j7a3-N72b-KsRB-uVxh-014U-q0erEO
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                16.00 GB
  Current LE             4096
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:1

  --- Logical volume ---
  LV Name                /dev/vlm1/home
  VG Name                vlm1
  LV UUID                qniVIM-2AXZ-vy4p-whbs-AS2m-adyu-dcIUlP
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                144.00 GB
  Current LE             36864
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:2

  --- Logical volume ---
  LV Name                /dev/vlm1/usr
  VG Name                vlm1
  LV UUID                Qbhux4-xbfb-VoYm-HHmZ-zRGq-uRtM-kudWjr
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                16.00 GB
  Current LE             4096
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           254:3

# mount
/dev/sda3 on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
procbususb on /proc/bus/usb type usbfs (rw)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/sda2 on /boot type ext3 (rw)
/dev/mapper/vlm1-home on /home type ext3 (rw)
/dev/mapper/vlm1-tmp on /tmp type ext3 (rw)
/dev/mapper/vlm1-usr on /usr type ext3 (rw)
/dev/mapper/vlm1-var on /var type ext3 (rw)
nfsd on /proc/fs/nfsd type nfsd (rw)

Proč se mi tam začaly při fdisk -l objevovat ty chyby s /dev/dm-X?