LVM情况下如何确定磁盘映射关系

系统有如下磁盘空间信息,说明一个boot分区,一个lvm:
[[email protected] mapper]# df -h
文件系统              容量  已用  可用 已用%% 挂载点
/dev/mapper/vg_gtlions-lv_root
2.2T   19G  2.1T   1% /
tmpfs                  32G     0   32G   0% /dev/shm
/dev/sda1             485M   59M  401M  13% /boot
通过fdisk查看磁盘,有两块盘,161GB的sda和2336GB的sdb,注意/dev/sda和/dev/sdb显示的都是物理信息,然后接着 /dev/mapper/vg_gtlions-lv_root和/dev/mapper/vg_gtlions-lv_swap是lvm逻辑信息:
[[email protected] mapper]# fdisk -l

Disk /dev/sda: 161.1 GB, 161061273600 bytes
255 heads, 63 sectors/track, 19581 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xd7099ee2

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64       19582   156773376   8e  Linux LVM

WARNING: GPT (GUID Partition Table) detected on ‘/dev/sdb’! The util fdisk doesn’t support GPT. Use GNU Parted.

Disk /dev/sdb: 2336.7 GB, 2336730644480 bytes
255 heads, 63 sectors/track, 284091 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      267350  2147483647+  ee  GPT

Disk /dev/mapper/vg_gtlions-lv_root: 2427.4 GB, 2427449245696 bytes
255 heads, 63 sectors/track, 295120 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/vg_gtlions-lv_swap: 69.8 GB, 69809995776 bytes
255 heads, 63 sectors/track, 8487 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
接着使用sar监控磁盘的时候出现的dev8-0、dev8-16、dev253-0和dev253-1之类的东西又是什么呢?
[[email protected] mapper]# sar -d 1 1
Linux 2.6.32-279.el6.x86_64 (gtlions)   2014年03月28日  _x86_64_        (32 CPU)

10时08分40秒       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
10时08分41秒    dev8-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
10时08分41秒   dev8-16      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
10时08分41秒  dev253-0      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
10时08分41秒  dev253-1      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00
[[email protected] mapper]# iostat 1 1
Linux 2.6.32-279.el6.x86_64 (gtlions)   2014年03月28日  _x86_64_        (32 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
0.01    0.00    0.29    0.23    0.00   99.47

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              19.99         2.04      2727.71     124446  166102906
sdb             289.48     35355.91     32758.29 2152986394 1994804816
dm-0           4575.29     35357.62     35486.00 2153090330 2160907704
dm-1              0.01         0.09         0.00       5592          0
这个其实是磁盘映射逻辑名称的关系,通过下面两个命令可以看的非常清楚,说明dev253-0 对应的是dm-0,:
[[email protected] mapper]# dmsetup ls
vg_gtlions-lv_swap      (253:1)
vg_gtlions-lv_root      (253:0)
[[email protected] mapper]# more /proc/partitions
major minor  #blocks  name

8        0  157286400 sda
8        1     512000 sda1
8        2  156773376 sda2
8       16 2281963520 sdb
8       17 2281961472 sdb1
253        0 2370555904 dm-0
253        1   68173824 dm-1
或者也可以查看下面信息:
[[email protected] mapper]# ll /dev/mapper/
总用量 0
crw-rw—- 1 root root 10, 58 3月  27 17:14 control
lrwxrwxrwx 1 root root      7 3月  27 17:14 vg_gtlions-lv_root -> ../dm-0
lrwxrwxrwx 1 root root      7 3月  27 17:14 vg_gtlions-lv_swap -> ../dm-1
[[email protected] vg_gtlions]# ll /dev/vg_gtlions
总用量 0
lrwxrwxrwx 1 root root 7 3月  27 17:14 lv_root -> ../dm-0
lrwxrwxrwx 1 root root 7 3月  27 17:14 lv_swap -> ../dm-1
还有其他相关的文件也可以查看,比如/dev/disk目录下的文件;
至于lvm和磁盘的映射关系还可以通过lvm的命令pvdisplay来查看。
-EOF-

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