CentOS六、7 LVM邏輯卷分區自動擴容Shell腳本編程思路與實例

應用場景和已知存在的問題：

1. 適用於CentOS6或CentOS7（可能適用於CentOS4或5等早些版本）

2. 根文件系統（被擴展的文件系統）採用LVM進行管理，例如mount命令輸出「/dev/mapper/vg_$hostname-lv_root on / type ext4 (rw)」中含有「mapper」關鍵詞

3. 自動擴容根文件系統，若是想擴展其餘文件系統，例若有的業務應用數據目錄不在根分區中，則須要修改Shell腳本代碼中的VG_PATH_TO_EXTEND變量（約78行）。

4. 僅支持ext二、ext三、ext四、xfs等分區格式的文件系統

5. 可能不支持某些過多自定義的CentOS系統，但核心步驟類似

6. 腳本中僅添加了scsi磁盤支持，如須要管理其餘磁盤，則須要本身擴充腳本

7. 爲了簡化腳本，避免執行屢次（本程序沒有寫執行鎖），先前已經存在的磁盤名已經設定爲sda，見Shell腳本代碼中第45行的ONLINE_SCSI_DISK_PRESENT變量

考慮點：

因爲CentOS6和CentOS7在默認根文件系統的文件系統格式存在差別，須要判斷是否爲xfs，若是是xfs則應該使用xfs_growfs而不是一味的使用resize2fs。

使用resize2fs擴展ext二、ext三、ext4格式的文件系統，使用xfs_growfs擴展xfs格式的文件系統

同一腳本在同一系統屢次被執行可能引起的錯誤，能夠考慮使用文件鎖來解決這個問題

編程思路：

1. （以前應該準備或檢查Shell腳本運行環境）獲取當前使用中的塊設備文件名

2. 獲取新添加scsi磁盤的文件名

3. 獲取LVM卷組名（vg）、將被擴展的卷組名的文件路徑

4. 將新添加磁盤使用fdisk建立分區並格式化爲LVM格式

5. 建立物理卷，pvcreate

6. 擴展卷組，vgextend

7. 調節邏輯卷大小，lvresize

8. 判斷是不是xfs文件系統

9. 同步文件系統，使得擴容生效

10. 返回系統磁盤使用狀況

Shell代碼：

#!/bin/bash
# Usage: Automatic expand lv with LVM managed disk # Setp 1: Add Hard Disk or Storage to Computing unit # Setp 2: Execute this script with root privilege # Setp 3: Mind info of this script execution result # Open the refrigerator door, get the shell script execution environment ready # Put the elephant into the refrigerator, how the shell scripts works # Close the refrigerator door, check out the result of execution # Simetimes, we have to pull new elephant or elephant dung out here, unset variables of shell script function check_execution_result(){  if [[ ! -z $RETVAL ]]; then   unset RETVAL  fi  RETVAL=$?  if [[ $RETVAL -ne 0 ]]; then   echo execution failed!   exit $RETVAL  else   echo execution successfully!  fi  unset RETVAL } # lsblk --scsi # lsblk --all # NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT # fd0 2:0 1 4K 0 disk # sda 8:0 0 40G 0 disk # ├─sda1 8:1 0 500M 0 part /boot # └─sda2 8:2 0 39.5G 0 part # ├─centos-swap 253:0 0 3.9G 0 lvm [SWAP] # └─centos-root 253:1 0 35.6G 0 lvm / # sdb 8:16 0 16G 0 disk # sr0 11:0 1 6.6G 0 rom # Show present scsi disk online # Q: Why use "xargs" here? # A: Convert the text from multi-line single-column into single-line multi-column, for sed operation ONLINE_SCSI_DISK_PRESENT=$(lsblk --all | grep disk | grep -v fd | awk '{print $1}' | xargs) # TODO # For execution this script beyond twice ONLINE_SCSI_DISK_PRESENT=sda # Find new scsi disk online # TODO figure it out why there is host0? echo "- - -" >/sys/class/scsi_host/host0/scan echo "- - -" >/sys/class/scsi_host/host1/scan echo "- - -" >/sys/class/scsi_host/host2/scan # Show new added scsi disk online ONLINE_SCSI_DISK_NEWADD=$(lsblk --all | grep disk | grep -v fd | awk '{print $1}' | xargs echo | sed "s/$ONLINE_SCSI_DISK_PRESENT//g") # Construct disk file with full path echo New Added SCSI Disk: $ONLINE_SCSI_DISK_NEWADD # Get VG Name VG_Name=$(vgdisplay | grep 'VG Name' | awk '{print $NF}') VG_PATH_TO_EXTEND=$(lvdisplay | grep 'LV Path' | awk '{print $NF}' | grep root) for BLOCK in $ONLINE_SCSI_DISK_NEWADD; do  ONLINE_SCSI_DISK_NEWADD_FILENAME="/dev/"$BLOCK  # end-of-file contents and eof mark must start row1  fdisk $ONLINE_SCSI_DISK_NEWADD_FILENAME >/dev/null 2>&1<<eof n p 1 t 8e w eof  check_execution_result  LVM_OPERATION_DISK_FILENAME=$ONLINE_SCSI_DISK_NEWADD_FILENAME"1"  pvcreate $LVM_OPERATION_DISK_FILENAME >/dev/null 2>&1  check_execution_result  vgextend $VG_Name $LVM_OPERATION_DISK_FILENAME >/dev/null 2>&1  check_execution_result  lvresize -l +100%FREE $VG_PATH_TO_EXTEND >/dev/null 2>&1  check_execution_result # resize2fs - ext2/ext3/ext4 file system resizer # xfs_growfs, xfs_info - expand an XFS filesystem #[root@hlc7172009 ~]# resize2fs /dev/mapper/centos-root #resize2fs 1.42.9 (28-Dec-2013) #resize2fs: Bad magic number in super-block while trying to open /dev/mapper/centos-root #Couldn't find valid filesystem superblock. #[root@hlc7172009 ~]# #[root@hlc7172009 ~]# xfs_growfs $VG_PATH_TO_EXTEND #meta-data=/dev/mapper/centos-root isize=256 agcount=4, agsize=2334208 blks # = sectsz=512 attr=2, projid32bit=1 # = crc=0 #data = bsize=4096 blocks=9336832, imaxpct=25 # = sunit=0 swidth=0 blks #naming =version 2 bsize=4096 ascii-ci=0 ftype=0 #log =internal bsize=4096 blocks=4559, version=2 # = sectsz=512 sunit=0 blks, lazy-count=1 #realtime =none extsz=4096 blocks=0, rtextents=0 #data blocks changed from 9336832 to 13530112 #[root@hlc7172009 ~]#  # Check xfs_info if is installed  which xfs_info >/dev/null 2>&1  if [[ $? -ne 0 ]]; then   yum install xfsprogs -y >/dev/null 2>&1  fi  # end Check xfs_info if is installed  # Check VG_PATH_TO_EXTEND if is xfs filesystem  xfs_info $VG_PATH_TO_EXTEND >/dev/null 2>&1  if [[ $? -ne 0 ]]; then   # is not xfs   VG_PATH_TO_EXTEND_IS_NOT_XFS=0  else   # is xfs   VG_PATH_TO_EXTEND_IS_NOT_XFS=1  fi  # end Check VG_PATH_TO_EXTEND if is xfs filesystem  # TODO CentOS7 default filesystem is xfs, so we can check it out by OS if is CentOS7  if [[ $VG_PATH_TO_EXTEND_IS_NOT_XFS ]]; then   # is xfs   xfs_growfs $VG_PATH_TO_EXTEND >/dev/null 2>&1  else   # is not xfs   resize2fs $VG_PATH_TO_EXTEND >/dev/null 2>&1  fi  check_execution_result  df -h  lsblk --all done 

測試結果：

（1）添加磁盤前：

（2）添加磁盤並執行腳本後：

因而可知根分區已經由原先的36GB變爲52GB，表示LVM擴容成功。

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• 本文來自：Linux教程網