linux-逻辑卷与分区对应关系

服务器使用逻辑卷，进行IO监控时，不确认分区对应的是哪个设备；
可通过下述方法来确认：


[root@localhost luly]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       50G   14G   33G  30% /
tmpfs                 3.9G     0  3.9G   0% /dev/shm
/dev/sda1             485M   36M  424M   8% /boot
/dev/mapper/VolGroup-lv_home
                      209G  190M  198G   1% /mail





[root@localhost luly]# iostat -x
Linux 2.6.32-220.el6.x86_64 (localhost.localdomain)     07/06/2012      _x86_64_        (8 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.18    0.00    0.27    0.68    0.00   98.86

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
sda               3.84  1842.64   13.92   15.30  3239.47 14863.94   619.43     4.88  167.12   1.58   4.61
dm-0              0.00     0.00    0.72   15.38   144.69   123.07    16.63     4.18  259.80   0.26   0.41
dm-1              0.00     0.00    4.82    5.43    38.59    43.48     8.00     3.10  302.48   0.09   0.09
dm-2              0.00     0.00   12.22 1837.17  3056.14 14697.40     9.60     6.70    3.62   0.02   4.41





[root@localhost luly]# lvdisplay
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_root
  VG Name                VolGroup
  LV UUID                RDbdK7-WPUJ-OzjM-1z5T-TEHj-Cj68-mKKnU7
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
  
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_home
  VG Name                VolGroup
  LV UUID                4xuokn-NhML-iv3t-hCI2-T8nd-oAT9-cwgOzo
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                211.95 GiB
  Current LE             54258
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
 Block device           253:2
  
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_swap
  VG Name                VolGroup
  LV UUID                W0RDNe-GL2v-yN6N-p8gp-VfHu-x8wS-BCNCO1
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                9.81 GiB
  Current LE             2512
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1


[root@localhost luly]# cat /etc/fstab

#
# /etc/fstab
# Created by anaconda on Sat Jun 30 01:26:25 2012
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/VolGroup-lv_root /                       ext4    defaults        1 1
UUID=69becaa0-60c9-426f-8729-8439fd0f5ba1 /boot                   ext4    defaults        1 2
/dev/mapper/VolGroup-lv_home /mail ext4    defaults,noatime,noexec,nodiratime,nodev 1 2
/dev/mapper/VolGroup-lv_swap swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0




通过三述四个命令，可以确认:
/对应dm-0
swap对应dm-1
/mail对应dm-2