LVM實作

環境準備:

1.新增一個硬碟:(利用VMware測試，使用100M)
*不重開機掃描硬碟方式:
#tail /vat/log/message    //確定沒抓到
#echo "- - -" > /sys/class/scsi-host/host0/scan    //重新掃描scsi硬碟
#tail /var/log/message    //應該就可看到

2.我的裝置為/dev/sdb
#fdisk /dev/sdb     //建立分割區，並設定id為"8e"

LVM相關指令:

	PV	VG	LV
掃描	pvscan	vgscan	lvscan
檢視	pvdisplay	vgdisplay	lvdisplay
新增	pvcreate	vgcreate	lvcreate
移除	pvremove	vgremove	lvremove
放大	none	vgextend	lvextend
縮小	none	vgreduce	lvreduce

設定:

1.新增一個PV
# pvcreate /dev/sdb1         
  Physical volume "/dev/sdb1" successfully created
# pvscan     //掃描PV
  PV /dev/sdb1                      lvm2 [101.98 MB]
  Total: 1 [101.98 MB] / in use: 0 [0   ] / in no VG: 1 [101.98 MB]
//  PV:/dev/sdb1  格式:lvm2
//PV大小[101.98MB] / 配置給VG的大小   /  沒有配置給VG剩餘大小

2.新增VG     //至少一個PV
# vgcreate mainVG /dev/sdb1
  Volume group "mainVG" successfully created
//指令格式:vgcreate   VGname   pv

# vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "mainVG" using metadata type lvm2
# pvscan
  PV /dev/sdb1   VG mainVG   lvm2 [100.00 MB / 100.00 MB free]
  Total: 1 [100.00 MB] / in use: 1 [100.00 MB] / in no VG: 0 [0   ]
//可以看到pv已經in use
*可以用display看到更詳細的內容

3.建立LV:     //建立完成後會產生目錄/dev/mainVG，LV會放在裡面
# ls /dev/mainVG            //應該找不到
# lvcreate  -L 50M -n LV01 mainVG
  Rounding up size to full physical extent 52.00 MB
  Logical volume "LV01" created
//指令格式:lvcreate -L size -n lvname VGname
# lvscan
  ACTIVE            '/dev/mainVG/LV01' [52.00 MB] inherit

4.mount LV
#mkfs.ext3 /dev/mainVG/LV01     //格式化LV
#mkdir /dir1
#mount /dev/mainVG/LV01 /dir1
//利用dd快速建立大檔，待會要練習放大縮小
#dd if=/dev/zero of=/dir1/test bs=1M count=10  //size:1M 做10次即為10M檔案

縮放LVM   ##容易造成data lost，請先備份在操作

1.放大 --先放大LV再放大檔案系統

# lvextend -L +30M /dev/mainVG/LV01   
  Rounding up size to full physical extent 32.00 MB
  Extending logical volume LV01 to 84.00 MB
  Logical volume LV01 successfully resized
//指令格式:lvextend -L 總大小/增加的大小:80M/+30M LVpath

//雖然成功但實際上還未變大，可用df檢查
# df |grep -B1 dir1
/dev/mapper/mainVG-LV01
                         51559     15237     33660  32% /dir1

# resize2fs /dev/mainVG/LV01    //放大可不用umount
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/mainVG/LV01 is mounted on /dir1; on-line resizing required
Performing an on-line resize of /dev/mainVG/LV01 to 86016 (1k) blocks.
The filesystem on /dev/mainVG/LV01 is now 86016 blocks long.

[root@a238 dir1]# df |grep -B1 dir1
/dev/mapper/mainVG-LV01
                         83363     15651     63619  20% /dir1

2.縮小 --先縮小檔案系統再縮小LV

增加PV:

1.再增加一個disk:/dev/sdc，同上處理分割區
2.加入VG

# pvcreate /dev/sdc1
  Physical volume "/dev/sdc1" successfully created
# vgextend mainVG /dev/sdc1
  Volume group "mainVG" successfully extended
# pvscan          //可以看出第二顆pv已正確加入mainVG
  PV /dev/sdb1   VG mainVG   lvm2 [100.00 MB / 16.00 MB free]
  PV /dev/sdc1   VG mainVG   lvm2 [100.00 MB / 100.00 MB free]
  Total: 2 [200.00 MB] / in use: 2 [200.00 MB] / in no VG: 0 [0   ]
# vgdisplay
  --- Volume group ---
  VG Name               mainVG
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               200.00 MB
  PE Size               4.00 MB
  Total PE              50
  Alloc PE / Size       21 / 84.00 MB
  Free  PE / Size       29 / 116.00 MB
  VG UUID               XK0Mvy-5b4U-pcBB-061Z-0dUJ-SBFR-Ro2yBf