RMAN备份遭遇ORA-235

This is the first time i post blog using English.

Today i get a ticket from EBR team(3rd part backup team), saying that the backup job fail due to ora-235:

so i go to the veritas netbackup path to check the backup log:

we see there are 2 backup log file today(2011-10-12). And one is backup fail, other is backup successful:

BACKUP FAIL LOG:

BACKUP SUCCESS LOG:

The backup fail due to ORA-00235 at 02:38am, and re-run the backup job at another time can be successfully.

The error happen because controlfile fixed table inconsistent due to concurrent update.

When we do the rman backup without catalog, just using controlfile to store backup information, it will read the controlfile and get the information like SCN from the controlfile.

When the database is doing a combination of a high rate of change, it will trigger redo log switch and when log switch, it will trigger checkpoint.

checkpoint operation will update the newest SCN to controlfile.

So the SCN is inconsistent with what we read at first time. ora-235 error raise.

From the netbackup log, we see the error happen at 10/12/2011 02:38:13.

From the log history, we also can see there are some log switch before 02:38:13.

So here we can get the root cause and solution:

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2条评论

  1. 大师您好,请教一下看这篇文章的几个问题。
    没能明白触发235这个错误的原因是什么(可能是俺英文水平有限),大概的理解是由于备份时的高数据读写访问导致的控制文件被更新。
    我的疑问是当我们做备份时,特别是大的库,可能要备1-2天才能备完的那种,中间不可能不发生检查点和日志切换吧,特别是白天业务高峰的时候,但是却从来没有遇到过这个错误。所以想请问触发这个错误到底是在哪种特殊的情况。
    谢谢您!

  2. re hctech:ora-235报错的原因是因为当redolog切出到archive log的时候,控制文件中会更新到最新的scn。更新之后,控制文件和rman会做同步,将最新scn的信息告诉给rman(如果你的rman使用的是nocatalog),如果日志切换的非常频繁,注意是非常频繁,以至于一直在更新scn,没有机会和rman做同步,因此就报错ora-235了。
    如果你的系统也有日志切换,但是没有频繁到我所说的这种程度,就不会引起ora-235的报错。

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