應用場景和已知存在的問題：
適用於CentOS6或CentOS7（可能適用於CentOS4或5等早些版本）
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
自動擴容根文件系統，如果想擴展其他文件系統，例如有的業務應用數據目錄不在根分區中，則需要修改Shell腳本代碼中的VG_PATH_TO_EXTEND變量（約78行）。
僅支持ext2、ext3、ext4、xfs等分區格式的文件系統
可能不支持某些過多自定義的CentOS系統，但核心步驟相似
腳本中僅添加了scsi磁盤支持，如需要管理其他磁盤，則需要自己擴充腳本
爲了簡化腳本，避免執行多次（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：
由於CentOS6和CentOS7在默認根文件系統的文件系統格式存在差異，需要判斷是否爲xfs，如果是xfs則應該使用xfs_growfs而不是一味的使用resize2fs。
使用resize2fs擴展ext2、ext3、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多次被執行可能引發的錯誤，可以考慮使用文件鎖來解決這個問題
編程思路：
（之前應該準備或檢查Shell腳本運行環境）獲取當前使用中的塊設備文件名
獲取新添加scsi磁盤的文件名
獲取LVM卷組名（vg）、將被擴展的卷組名的文件路徑
將新添加磁盤使用fdisk創建分區並格式化爲LVM格式
創建物理卷，pvcreate
擴展卷組，vgextend
調節邏輯卷大小，lvresize
判斷是否是xfs文件系統
同步文件系統，使得擴容生效
返回系統磁盤使用情況
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 $RETVAL else echo execution successfully!
fi unset RETVAL
}# lsblk --scsi# lsblk --all# NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT# fd0 2:0 1 4K 0 disk
# sda 8:0 0 40G 0 disk
# ├─sda1 8:1 0 500M 0 part /boot# └─sda2 8:2 0 39.5G 0 part
# ├─centos-swap 253:0 0 3.9G 0 lvm [SWAP]# └─centos-root 253:1 0 35.6G 0 lvm /# sdb 8:16 0 16G 0 disk
# sr0 11:0 1 6.6G 0 rom
# Show present scsi disk online# Q: Why use "xargs" here?# A: Convert the text from multi-line single-column into single-line multi-column, for sed operationONLINE_SCSI_DISK_PRESENT=$(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 $ONLINE_SCSI_DISK_NEWADD_FILENAME >/dev/null 2>&1<<eof
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eof check_execution_result LVM_OPERATION_DISK_FILENAME=$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：
由此可見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