CentOS6、7 LVM逻辑卷分区自动扩容Shell脚本编程思路与实例

应用场景和已知存在的问题：

适用于CentOS6或CentOS7（可能适用于CentOS4或5等早些版本）
根文件系统（被扩展的文件系统）采用LVM进行管理，例如mount命令输出“/dev/mapper/vg_$hostname-lv_root on / type ext4 (rw)”中含有“mapper”关键词
自动扩容根文件系统，如果想扩展其他文件系统，例如有的业务应用数据目录不在根分区中，则需要修改Shell脚本代码中的VG_PATH_TO_EXTEND变量（约78行）。
仅支持ext2、ext3、ext4、xfs等分区格式的文件系统
可能不支持某些过多自定义的CentOS系统，但核心步骤相似
脚本中仅添加了scsi磁盘支持，如需要管理其他磁盘，则需要自己扩充脚本
为了简化脚本，避免执行多次（本程序没有写执行锁），先前已经存在的磁盘名已经设定为sda，见Shell脚本代码中第45行的ONLINE_SCSI_DISK_PRESENT变量

考虑点：

由于CentOS6和CentOS7在默认根文件系统的文件系统格式存在差异，需要判断是否为xfs，如果是xfs则应该使用xfs_growfs而不是一味的使用resize2fs。使用resize2fs扩展ext2、ext3、ext4格式的文件系统，使用xfs_growfs扩展xfs格式的文件系统同一脚本在同一系统多次被执行可能引发的错误，可以考虑使用文件锁来解决这个问题

编程思路：

（之前应该准备或检查Shell脚本运行环境）获取当前使用中的块设备文件名
获取新添加scsi磁盘的文件名
获取LVM卷组名（vg）、将被扩展的卷组名的文件路径
将新添加磁盘使用fdisk创建分区并格式化为LVM格式
创建物理卷，pvcreate
扩展卷组，vgextend
调节逻辑卷大小，lvresize
判断是否是xfs文件系统
同步文件系统，使得扩容生效
返回系统磁盘使用情况

Shell代码：

#!/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 $RETVAL  else    echo execution successfully!
fi  unset RETVAL
}# lsblk --scsi# lsblk --all# NAME	    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT# fd0	       2:0    1    4K  0 disk
# sda	       8:0    0   40G  0 disk
# ├─sda1	    8:1    0  500M  0 part /boot# └─sda2	    8:2    0 39.5G  0 part
#   ├─centos-swap 253:0    0  3.9G  0 lvm  [SWAP]#   └─centos-root 253:1    0 35.6G  0 lvm  /# sdb	       8:16   0   16G  0 disk
# sr0	      11:0    1  6.6G  0 rom
# Show present scsi disk online# Q: Why use "xargs" here?# A: Convert the text from multi-line single-column into single-line multi-column, for sed operationONLINE_SCSI_DISK_PRESENT=$(lsblk --all | grep disk | grep -v fd | awk '{print $1}' | xargs)# TODO# For execution this script beyond twiceONLINE_SCSI_DISK_PRESENT=sda# Find new scsi disk online# TODO figure it out why there is host0?
echo "- - -" >/sys/class/scsi_host/host0/scan
echo "- - -" >/sys/class/scsi_host/host1/scan
echo "- - -" >/sys/class/scsi_host/host2/scan# Show new added scsi disk onlineONLINE_SCSI_DISK_NEWADD=$(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: $ONLINE_SCSI_DISK_NEWADD# Get VG NameVG_Name=$(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 $ONLINE_SCSI_DISK_NEWADD_FILENAME >/dev/null 2>&1<<eof
n
p1
t8e
w
eof  check_execution_result  LVM_OPERATION_DISK_FILENAME=$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

测试结果：

（1）添加磁盘前：

（2）添加磁盘并执行脚本后：

由此可见根分区已经由原先的36GB变为52GB，表示LVM扩容成功。--END--本文来自：Linux教程网