最近，我維護的cloud環境DB部分計劃維護，需要在本地快速搭建一個相同的模擬環境。cloud環境的DB部分架構如下：

      雙機+mysql+HA+DRBD

    為了實現測試環境的快速搭建，放棄了從頭搭建環境的方法，而是選擇將cloud環境的兩個節點機器上的linux進行完整備份，然後在測試環境上恢復，實現環境複製的效果。具體步驟如下：

1）將現有環境的進行備份
tar cvpzf backup.tgz / --exclude=/DB --exclude=/boot  --exclude=/proc --exclude=/dev  --exclude=/mnt --exclude=/media --exclude=/lost+found --exclude=/backup.tgz  --exclude=/sys
2）將備份遷移到新機器
tar xvpfz backup.tgz -C /  
3）修改root賬戶密碼
#passwd root
4）修改網路配置，重啟網路生效
5）臨時設定drbd，heartbeat為開機不啟動，等設定好以後再恢復
#chkconfig drbd off
#chkconfig heartbeat off

6）在測試機器上建立drbd資源

#lvremove /dev/VG001/LV_DB
#lvcreate -l 1308 -n LV_DB VG001       
#drbdadm create-md all     
#/etc/init.d/drbd start
#drbdadm -- --overwrite-data-of-peer primary r0   （只在主節點操作）  
Or # drbdsetup /dev/drbd0 primary -o
#mkfs.ext3 /dev/drbd0
#mount /dev/drbd0 /DB

7）配置mysql

mysqladmin -h localhost -u root password Trend#100  
mysql -hlocalhost -uroot -pTrend#100      
mysql> GRANT ALL PRIVILEGES ON *.* TO

將/etc/ha.d/resource.d目錄下的mysqld檔案替換為資料夾中的同名檔案（修改/etc/init.d/mysqld檔案中的start部分）
/etc/init.d/heartbeat start

恢復開機自啟動
#chkconfig -- add drbd   
#chkconfig drbd on
#chkconfig -- add heartbeat   
#chkconfig heartbeat on

過程中出現的錯誤，及處理辦法

1.
[[email protected] ~]# mkfs.ext3 /dev/drbd0
mke2fs 1.39 (29-May-2006)
mkfs.ext3: Wrong medium type while trying to determine filesystem size

或者
[[email protected] ~]# mount /dev/drbd0 /DB
mount: block device /dev/drbd0 is write-protected, mounting read-only
mount: Wrong medium type

解決辦法：#drbdadm -- --overwrite-data-of-peer primary r0

2.
[[email protected] ~]# /etc/init.d/drbd start
Starting DRBD resources: [ d(r0) s(r0) n(r0) ]..........
***************************************************************
 DRBD's startup script waits for the peer node(s) to appear.
 - In case this node was already a degraded cluster before the
   reboot the timeout is 120 seconds. [degr-wfc-timeout]
 - If the peer was available before the reboot the timeout will
   expire after 0 seconds. [wfc-timeout]
   (These values are for resource 'r0'; 0 sec -> wait forever)
 To abort waiting enter 'yes' [ -- ]:[  10]:[  11]:[  12]:[  13]:ye
解決辦法：用setup命令關閉防火牆或者開通相應埠

3.mysqld不能被heartbeat喚起
解決辦法：原因是/etc/ha.d/haresources檔案配置中service每被正確喚起
  #ln -s /etc/init.d/mysqld /etc/ha.d/resource.d/mysqld

4.[[email protected] data]# /etc/init.d/mysqld start
Timeout error occurred trying to start MySQL Daemon.
Starting MySQL:  [FAILED]
解決辦法：
  #cd /DB/
  #rm -rf data
  #/usr/bin/mysql_install_db
  instead of running service mysqld start or service mysqld restart try running:
  # service mysqld stop; mysqld_safe &
5.[[email protected] resource.d]# /etc/init.d/mysqld status
mysqld dead but subsys locked
解決辦法：手工執行 #service mysqld stop; mysqld_safe &

6.登陸時報以下錯誤

Unable to get valid context for root
Last login: Wed Jul 24 02:06:01 2013 from 10.64.41.3

單機模式進入後#vi /var/log/secure

Jul 24 02:20:46 JDC2-TMSP-SQL1-NEW sshd[4372]: Accepted password for root from 10.64.41.3 port 60506 ssh2
Jul 24 02:20:46 JDC2-TMSP-SQL1-NEW sshd[4372]: pam_selinux(sshd:session): Security context unconfined_u:system_r:abrt_helper_t:s0-s0:c0.c1023 is not allowed for unconfined_u:system_r:abrt_helper_t:s0-s0:c0.c1023
Jul 24 02:20:46 JDC2-TMSP-SQL1-NEW sshd[4372]: pam_selinux(sshd:session): Unable to get valid context for root
Jul 24 02:20:46 JDC2-TMSP-SQL1-NEW sshd[4372]: pam_unix(sshd:session): session opened for user root by (uid=0)
Jul 24 02:20:47 JDC2-TMSP-SQL1-NEW sshd[4372]: error: ssh_selinux_setup_pty: security_compute_relabel: Invalid argument

解決辦法：進入單機模式，關閉SElinux

關閉SElinux不重啟系統的方法
Redhat系統，修改/etc/sysconfig/selinux檔案：

#SELINUX=enforcing
SELINUX=disabled

重啟生效，如果不想重啟，用命令
setenforce 0