[20170309]关于在线日志与归档2.txt-白红宇

[20170309]关于在线日志与归档2.txt

--//当日志写满了,或者执行手工了切换,再或者rman备份时有时也会触发日志切换:

alter system switch logfile ;

alter system archive log current ;

--//本文简单探究日志归档是如何保存的.探查日志文件头块.

1.环境:

--//启动到mount状态.

SYS@book> @ &r/ver

BANNER

--------------------------------------------------------------------------------

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

SYS@book> @ &r/logfile

GROUP# STATUS TYPE MEMBER IS_ GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIME NEXT_CHANGE# NEXT_TIME

------ ---------- ---------- ------------------------------- --- ------ ------- --------- ----------- --------- ------- --- ---------- ------------- ------------------- ------------ -------------------

1 ONLINE /mnt/ramdisk/book/redo01.log NO 1 1 695 52428800 512 1 YES INACTIVE 13276910949 2017-02-28 14:40:12 13276931102 2017-03-09 10:01:48

2 ONLINE /mnt/ramdisk/book/redo02.log NO 2 1 696 52428800 512 1 YES INACTIVE 13276931102 2017-03-09 10:01:48 13276931986 2017-03-09 10:02:36

3 ONLINE /mnt/ramdisk/book/redo03.log NO 3 1 697 52428800 512 1 NO CURRENT 13276931986 2017-03-09 10:02:36 2.814750E+14

4 STANDBY /mnt/ramdisk/book/redostb01.log NO

5 STANDBY /mnt/ramdisk/book/redostb02.log NO

6 STANDBY /mnt/ramdisk/book/redostb03.log NO

7 STANDBY /mnt/ramdisk/book/redostb04.log NO

7 rows selected.

--//仅仅拿seq#=696 来研究.

$ ls -l /mnt/ramdisk/book/redo02.log /u01/app/oracle/archivelog/book/1_696_896605872.dbf

-rw-r----- 1 oracle oinstall 52429312 2017-03-09 10:02:36 /mnt/ramdisk/book/redo02.log

-rw-r----- 1 oracle oinstall 1626112 2017-03-09 10:02:38 /u01/app/oracle/archivelog/book/1_696_896605872.dbf

--//前面我们探查了日志文件的OS块.下面将继续探究日志的文件头块1.

2.取出文件头保存为二进制以及转储格式

$ dd if=/mnt/ramdisk/book/redo01.log bs=512 count=1 skip=1 of=r1.dd

1+0 records in

1+0 records out

512 bytes (512 B) copied, 6.5894e-05 seconds, 7.8 MB/s

$ dd if=/u01/app/oracle/archivelog/book/1_696_896605872.dbf bs=512 count=1 skip=1 of=d1.dd

1+0 records in

1+0 records out

512 bytes (512 B) copied, 5.7258e-05 seconds, 8.9 MB/s

$ xxd -c 16 d1.dd > d1.txt

$ xxd -c 16 r1.dd > r1.txt

$ diff r1.txt d1.txt

1c1

< 0000000: 0122 0000 0100 0000 b802 0000 0080 c7b6 ."............?

---

> 0000000: 0122 0000 0100 0000 b802 0000 0080 d6b6 ."............?

15c15

< 00000e0: 0300 0000 0c4c eb37 0000 0000 0000 8000 .....L?........

---

> 00000e0: 0300 0000 0c4c eb37 0000 0000 1100 8000 .....L?........

--//偏移0x14-0x15是检查和,对于日志文件.仅仅修改了 0xeb-0xef出为0x00008000->0x11008000.

SYS@book> alter system dump logfile '/u01/app/oracle/archivelog/book/1_696_896605872.dbf' validate;

System altered.

DUMP OF REDO FROM FILE '/u01/app/oracle/archivelog/book/1_696_896605872.dbf'

Opcodes *.*

RBAs: 0x000000.00000000.0000 thru 0xffffffff.ffffffff.ffff

SCNs: scn: 0x0000.00000000 thru scn: 0xffff.ffffffff

Times: creation thru eternity

VALIDATE ONLY

FILE HEADER:

Compatibility Vsn = 186647552=0xb200400

Db ID=1337401710=0x4fb7216e, Db Name='BOOK'

Activation ID=1337448558=0x4fb7d86e

Control Seq=36178=0x8d52, File size=102400=0x19000

File Number=2, Blksiz=512, File Type=2 LOG

descrip:"Thread 0001, Seq# 0000000696, SCN 0x0003175de41e-0x0003175de792"

thread: 1 nab: 0xc68 seq: 0x000002b8 hws: 0x3 eot: 0 dis: 0

resetlogs count: 0x35711eb0 scn: 0x0000.000e2006 (925702)

prev resetlogs count: 0x3121c97a scn: 0x0000.00000001 (1)

Low scn: 0x0003.175de41e (13276931102) 03/09/2017 10:01:48

Next scn: 0x0003.175de792 (13276931986) 03/09/2017 10:02:36

Enabled scn: 0x0000.000e2006 (925702) 11/24/2015 09:11:12

Thread closed scn: 0x0003.175de41e (13276931102) 03/09/2017 10:01:48

Disk cksum: 0xb6d6 Calc cksum: 0xb6d6

Terminal recovery stop scn: 0x0000.00000000

Terminal recovery 01/01/1988 00:00:00

Most recent redo scn: 0x0000.00000000

Largest LWN: 283 blocks

End-of-redo stream : No

Unprotected mode

Miscellaneous flags: 0x800011

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thread internal enable indicator: thr: 0, seq: 0 scn: 0x0000.00000000

Zero blocks: 8

Format ID is 2

redo log key is 635b658f7133c1a828b05e569341c54e

redo log key flag is 5

Enabled redo threads: 1

END OF REDO DUMP

$ egrep "^DUMP|^ Miscellaneous" /u01/app/oracle/diag/rdbms/book/book/trace/book_ora_20294.trc

DUMP OF REDO FROM FILE '/u01/app/oracle/archivelog/book/1_696_896605872.dbf'

Miscellaneous flags: 0x800011

DUMP OF REDO FROM FILE '/u01/app/oracle/archivelog/book/1_695_896605872.dbf'

Miscellaneous flags: 0x802011

DUMP OF REDO FROM FILE '/mnt/ramdisk/book/redo02.log'

Miscellaneous flags: 0x800000

--//感觉就是前面0x80足够.

3.再看看别的服务器:

select 'alter system dump logfile ''' ||name || ''' validate;' from v$archived_log where dest_id=1 and name is not null order by stamp desc,name;

--输出保存文件,执行它:

--//服务器1:

$ egrep "^ Miscellaneous" xxxxx_ora_29111.trc | uniq -c

100 Miscellaneous flags: 0x800011

--//可以发现仅仅就是修改0x2eb-0x2fe 为0x1100,全是0x800011.

--//服务器1:

$ egrep "^ Miscellaneous" /u01/app/oracle/diag/rdbms/xxxx/xxxx1/trace/xxxx_ora_16752.trc | sort |uniq -c

78 Miscellaneous flags: 0x800011

13 Miscellaneous flags: 0x800021

--//嗯,存在2种可能.

$ egrep "^DUMP|^ Miscellaneous" /u01/app/oracle/diag/rdbms/xxxx/xxxx1/trace/xxxx1_ora_16752.trc | grep -B1 0x800021 | grep "'" | cut -d" " -f6

'+RECOC1/xxxx/archivelog/2017_03_09/thread_2_seq_2695.564.938158875'

'+RECOC1/xxxx/archivelog/2017_03_08/thread_1_seq_3401.388.938060823'

'+RECOC1/xxxx/archivelog/2017_03_07/thread_2_seq_2690.1139.937974461'

'+RECOC1/xxxx/archivelog/2017_03_04/thread_2_seq_2683.420.937715223'

'+RECOC1/xxxx/archivelog/2017_03_03/thread_2_seq_2681.1194.937628857'

'+RECOC1/xxxx/archivelog/2017_03_01/thread_2_seq_2676.1138.937456023'

'+RECOC1/xxxx/archivelog/2017_02_28/thread_2_seq_2674.1242.937110459'

'+RECOC1/xxxx/archivelog/2017_02_25/thread_2_seq_2668.951.936851263'

'+RECOC1/xxxx/archivelog/2017_02_24/thread_2_seq_2665.1050.936764823'

'+RECOC1/xxxx/archivelog/2017_02_23/thread_1_seq_3359.1085.936714747'

'+RECOC1/xxxx/archivelog/2017_02_23/thread_2_seq_2663.344.936714739'

'+RECOC1/xxxx/archivelog/2017_02_23/thread_1_seq_3357.832.936714663'

'+RECOC1/xxxx/archivelog/2017_02_23/thread_2_seq_2661.907.936689855'