耐心，再耐心些

· 作者 小荷||【转载时请务必以超链接形式标明文章原始出处和作者信息】
· 永久链接: http://www.oracleblog.cn/working-case/patience-and-more-patience/

某数据库主机突然掉电，重启数据库库后进行实例恢复，没想到这个恢复一直进行了近一个小时，唉，当时真有shutdown abort重来的冲动了，幸好没做！真是想不明白，oracle的前滚要做这么长的时间！

50分钟的内，做了38384 data blocks的recovery，按照8k一个db block，大约也就是300M左右的数据做恢复。不过竟然等了50分钟，这个时间确实有点长了。

ALTER DATABASE   MOUNT
Thu Jul 17 23:40:34 2008
Successful mount of redo thread 1, with mount id 2819316398
Thu Jul 17 23:40:34 2008
Database mounted in Exclusive Mode.
Completed: ALTER DATABASE   MOUNT
Thu Jul 17 23:40:35 2008
ALTER DATABASE OPEN
Thu Jul 17 23:53:00 2008
Beginning crash recovery of 1 threads
Thu Jul 17 23:54:12 2008
Started redo scan
Thu Jul 17 23:55:00 2008
Completed redo scan
 96595 redo blocks read, 38384 data blocks need recovery
---------  这边，等待了近50分钟 -----------------------------
Fri Jul 18 00:41:59 2008
Started recovery at
 Thread 1: logseq 54295, block 335001, scn 0.0
Fri Jul 18 00:41:59 2008
Recovery of Online Redo Log: Thread 1 Group 3 Seq 54295 Reading mem 0
  Mem# 0 errs 0: /dev/vg_ora1/rredo31
  Mem# 1 errs 0: /dev/vg_ora2/rredo32
Fri Jul 18 00:44:23 2008
Completed redo application
---- 这边，也等了近10分钟 ------------------------
Fri Jul 18 00:56:50 2008
Ended recovery at
 Thread 1: logseq 54295, block 431596, scn 4.3244460870
 38384 data blocks read, 38384 data blocks written, 96595 redo blocks read
Crash recovery completed successfully
Fri Jul 18 00:56:56 2008
LGWR: Primary database is in CLUSTER CONSISTENT mode
FAST_START_MTTR_TARGET 300 is out of the valid MTTR range, use 394 instead.
Thread 1 advanced to log sequence 54296
Thread 1 opened at log sequence 54296
  Current log# 1 seq# 54296 mem# 0: /dev/vg_ora1/rredo11
  Current log# 1 seq# 54296 mem# 1: /dev/vg_ora2/rredo12
Successful open of redo thread 1
Fri Jul 18 00:56:57 2008
SMON: enabling cache recovery
Fri Jul 18 00:56:57 2008
ARC0: Evaluating archive   log 3 thread 1 sequence 54295
ARC0: Beginning to archive log 3 thread 1 sequence 54295
Creating archive destination LOG_ARCHIVE_DEST_1: '/arch/hnmisc_1_54295.arc'
Fri Jul 18 00:56:57 2008
Successfully onlined Undo Tablespace 51.
Fri Jul 18 00:56:57 2008
SMON: enabling tx recovery
Fri Jul 18 00:56:57 2008
Database Characterset is ZHS16GBK
replication_dependency_tracking turned off (no async multimaster replication found)
Completed: ALTER DATABASE OPEN

另外，这边再提一下redo log的计算：
每个redo block的大小：

SQL> select max(lebsz) from x$kccle;
 
MAX(LEBSZ)
----------
      1024

96595 redo blocks read，即在做前滚的时候，96595×1024/1024=96595 KB的redo被读取了。

· 【文章发布信息】发表于： 2008-07-19 @ 01:38:24 · ||分类： ..experience, Working case

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