讲述方法如何进行数据库系统的备份!有那些注意事项
INFORMIX数据库系统备份采用ontape为备份工具,分零级备份、一级备份和二级备份。零级备份是对整个系统的备份;一级备份是对系统在零级备份基础上的增量备份;二级备份则是在一级备份基础上对系统的备份。三种备份的步骤类似,以零级备份为例,过程如下:
将用于作0级备份的磁带插入指定的磁带机。
以informix用户注册,执行如下命令:
$ontape -s
Please enter the level of archive to be performed(0,1,or2)
输入0,按回车键
Please mount tape 1 on /dev/rmt/0m and press Return to continue.
确认磁带已准备好,按回车键
percent done
percent done
…
percent done
Please label this tape as number 1 in the arc tape sequence.
This tape contains the following logical logs:
Program over
如果一盘磁带无法备完所有数据,则可能出现如下情况:
percent done
Tape is full…
Please label this tape as number 1 in the arc tape sequence.
This tape contains the following logical logs:
Please mount tape 2 on /dev/rmt0 and press Return to continue…
这时请放好第二盘磁带,否则系统会提示
warming: previous tape is still mounted!
Please mount tape 2 on/dev/rmt0 and press Retum to continue…
Percent done
Please label this tape as number 2 in the arc tape sequence.
Program over.
则改磁带包含了零级备份与以前的逻辑日志。
请正确标记号此盘磁带,并请妥善保存。
作零级备份需注意如下一些事情:
在备份之前,确信已将$INFORMIXDIR/etc/onconfig.clr文件中的数据库备份设备设置成用以作0级备份的磁带设备,并设置正确的块尺寸(TAPEBLK)与磁带容量(TAPESIZE):
TAPEDEV /dev/rmt/0m
TAPEBLK 512 (K)
TAPESIZE 2048000 (K)
确认磁带机与磁带完好可用
注意不要覆盖仍然有用的备份磁带