[20161111File Space Bitmap Block修复机制

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#数据库

本文详细探讨了Oracle数据库中FileSpaceBitmapBlock的修复机制。通过实验验证了当位图区被全部设置为1后，如何通过dbms_space_admin.TABLESPACE_REBUILD_BITMAPS过程进行修复。文章还分析了修复过程中涉及的后台操作和技术细节。

[20161111]File Space Bitmap Block修复机制.txt

--前几天在测试File Space Bitmap Block时执行了，execute dbms_space_admin.TABLESPACE_REBUILD_BITMAPS('SUGAR')
--这样位图区全部设置为1,显示都是F。它的修复机制不是非常清楚，今天做一些深入的探究。

--继续重复昨天的测试。

1.环境：
SCOTT@book> @ &r/ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

CREATE TABLESPACE SUGAR DATAFILE
  '/mnt/ramdisk/book/sugar01.dbf' SIZE 40M AUTOEXTEND ON NEXT 16M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON;

create table t1 tablespace sugar as select rownum id ,lpad('A',32,'A') name from dual connect by level<=1e5;
--建立大小5M的表。

create table t2 tablespace sugar as select rownum id ,lpad('B',32,'B') name from dual connect by level<=2e5;
create table t3 tablespace sugar as select rownum id ,lpad('C',32,'C') name from dual connect by level<=2e5;
alter system checkpoint;

2.转储位图区信息：

SYS@book> execute dbms_space_admin.tablespace_dump_bitmaps('SUGAR');
PL/SQL procedure successfully completed.

Header Control:
RelFno: 6, Unit: 8, Size: 5120, Flag: 9
AutoExtend: YES, Increment: 2048, MaxSize: 4194302
Initial Area: 126, Tail: 5119, First: 400, Free: 224
Deallocation scn: 925704.0
Header Opcode:
Save: No Pending Op
File Space Bitmap Block:
BitMap Control:
RelFno: 6, BeginBlock: 128, Flag: 0, First: 400, Free: 63088
FFFFFFFFFFFFFFFF FFFFFFFFFFFFFFFF FFFFFFFFFFFFFFFF FFFFFFFFFFFFFFFF
FFFFFFFFFFFFFFFF FFFFFFFFFFFFFFFF FFFF000000000000 0000000000000000
0000000000000000 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 0000000000000000 0000000000000000

$ bvi -b 24576 -s 8192 /mnt/ramdisk/book/sugar01.dbf
00006000  1E A2 00 00 03 00 80 01 25 DC 5F 00 00 00 01 04 5B B1 00 00 06 00 00 00 80 00 00 00 00 00 00 00 ........%._.....[...............
00006020  90 01 00 00 70 F6 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF ....p...........................
00006040  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006060  FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
00006080  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
000060A0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
000060C0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................

-- 偏移 60 后仅仅 10个 FF。

--关闭数据库重新启动，并且dba 6,3 全部FF变为00.注意其他不动，注意要重新计算检查和。

BBED> sum
Check value for File 6, Block 3:
current = 0xb15b, required = 0x4ea4

BBED> sum apply dba 6,3
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
Check value for File 6, Block 3:
current = 0x4ea4, required = 0x4ea4

--启动数据库。
SYS@book> @ &r/bh 6 3
no rows selected

--可以发现现在该数据块没有在数据缓存中。

3.分析执行过程：

SYS@book> @ &r/spid

       SID    SERIAL# SPID       PID  P_SERIAL# C50
---------- ---------- ------ ------- ---------- --------------------------------------------------
       232          7 5574        21          4 alter system kill session '232,7' immediate;


--打开另外终端执行：
$ strace -f -p 5574 -o /tmp/map.txt

--切换回去：
SYS@book> execute dbms_space_admin.TABLESPACE_REBUILD_BITMAPS('SUGAR');
PL/SQL procedure successfully completed.

$ bvi -b 24576 -s 8192 /mnt/ramdisk/book/sugar01.dbf
00006000  1E A2 00 00 03 00 80 01 B7 D6 5F 00 00 00 02 04 44 41 00 00 06 00 00 00 80 00 00 00 00 00 00 00 .........._.....DA..............
00006020  00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF ................................
00006040  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006060  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006080  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060A0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060C0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060E0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006100  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006120  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006140  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006160  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006180  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000061A0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000061C0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000061E0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006200  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006220  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006240  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006260  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006280  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000062A0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000062C0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000062E0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................

--你可以发现数据文件的位图区块里面全是F。表示已经使用，而实际上你检查对应的内存块：

SYS@book> @ &r/bh 6 3
HLADDR              DBARFIL     DBABLK      CLASS CLASS_TYPE         STATE             TCH CR_SCN_BAS CR_SCN_WRP CR_UBA_FIL CR_UBA_BLK CR_UBA_SEQ BA               OBJECT_NAME
---------------- ---------- ---------- ---------- ------------------ ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------- --------------------
0000000084B84748          6          3         12 bitmap index block free                0          0          0          0          0          0 00000000756A8000
0000000084B84748          6          3         12 bitmap index block xcur                1          0          0          0          0          0 00000000756AA000

--STATE=xcur BA=00000000756AA000
--你可以发现FF从32+24=56 开始，56 = 0x38

SYS@book> oradebug setmypid
Statement processed.

SYS@book> oradebug peek 0x00000000756AA000 16
[0756AA000, 0756AA010) = 0000A21E 01800003 005FDC25 00010000

--00006000  1E A2 00 00 03 00 80 01 B7 D6 5F 00 00 00 02 04 44 41 00 00 06 00 00 00 80 00 00 00 00 00 00 00 .........._.....DA..............
                        ~~~~~~~~~~~
--大小头对调可以发现的dba地址一致。

SYS@book> oradebug peek 0x00000000756AA038 16
[0756AA038, 0756AA048) = FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF
--全是FF

SYS@book> oradebug peek 0x00000000756AA060 16
[0756AA060, 0756AA070) = FFFFFFFF FFFFFFFF 0000FFFF 00000000

SYS@book> oradebug peek 0x00000000756AA100 16
[0756AA100, 0756AA110) = 00000000 00000000 00000000 00000000

--而偏移量0x100= 256，全都是00.也就是内存中的数据块是正确，由此可以推出他的恢复机制，先修改数据块设置FF，读取到缓存中然
--后扫描分析数据块，在内存数据块中标识那些块使用了。

--如果你发出alter system checkpoint，这样内存的信息写到数据文件中，结果就是正确的。

SYS@book> alter system checkpoint;
System altered.

SYS@book> @ &r/bh 6 3
old  23:   dbarfil = &1 and
new  23:   dbarfil = 6 and
old  24:   dbablk = &2
new  24:   dbablk = 3
HLADDR              DBARFIL     DBABLK      CLASS CLASS_TYPE         STATE             TCH CR_SCN_BAS CR_SCN_WRP CR_UBA_FIL CR_UBA_BLK CR_UBA_SEQ BA               OBJECT_NAME
---------------- ---------- ---------- ---------- ------------------ ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------- --------------------
0000000084B84748          6          3         12 bitmap index block free                0          0          0          0          0          0 00000000756A8000
0000000084B84748          6          3         12 bitmap index block xcur                1          0          0          0          0          0 00000000756AA000

$ bvi -b 24576 -s 8192 /mnt/ramdisk/book/sugar01.dbf
00006000  1E A2 00 00 03 00 80 01 25 DC 5F 00 00 00 01 04 5B B1 00 00 06 00 00 00 80 00 00 00 00 00 00 00 ........%._.....[...............
00006020  90 01 00 00 70 F6 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF ....p...........................
00006040  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006060  FF FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
00006080  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
000060A0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
000060C0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................
000060E0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................................

--可以发现已经修复了。根本不需要担心开始全部写入FF，标识全部使用，实际上内存对应的数据块是正确的。

4.深入分析：

--检查跟踪文件
# ls -l /proc/5574/fd
total 0
lr-x------ 1 oracle oinstall 64 2016-11-11 10:52:23 0 -> /dev/null
l-wx------ 1 oracle oinstall 64 2016-11-11 10:52:23 1 -> /dev/null
l-wx------ 1 oracle oinstall 64 2016-11-11 10:52:23 12 -> pipe:[19152388]
l-wx------ 1 oracle oinstall 64 2016-11-11 10:52:23 2 -> /dev/null
lrwx------ 1 oracle oinstall 64 2016-11-11 10:54:01 256 -> /mnt/ramdisk/book/sugar01.dbf
lrwx------ 1 oracle oinstall 64 2016-11-11 10:54:01 258 -> /mnt/ramdisk/book/system01.dbf
lr-x------ 1 oracle oinstall 64 2016-11-11 10:52:23 3 -> /dev/null
lr-x------ 1 oracle oinstall 64 2016-11-11 10:52:23 4 -> /u01/app/oracle/product/11.2.0.4/dbhome_1/rdbms/mesg/oraus.msb
lr-x------ 1 oracle oinstall 64 2016-11-11 10:52:23 5 -> /proc/5574/fd
lr-x------ 1 oracle oinstall 64 2016-11-11 10:52:23 6 -> /dev/zero
lrwx------ 1 oracle oinstall 64 2016-11-11 10:52:23 7 -> /u01/app/oracle/admin/book/adump/book_ora_5574_20161111105146035812143795.aud
lr-x------ 1 oracle oinstall 64 2016-11-11 10:52:23 9 -> pipe:[19152387]

$ grep write /tmp/map.txt
5197  write(12, "\0\265\0\0\6\0\0\0\0\0\10\6\0\274\333_\0\0\0\0\0\10\0\0\0\0\0\0\0\0\0\0"..., 181) = 181
5197  write(12, "\0\21\0\0\6\0\0\0\0\0\t\1\0\0\0\0\0", 17) = 17
--写很少，不知道什么回事。

$ grep pread /tmp/map.txt
5197  pread(258, "\6\242\0\0008\17@\0\271v\16\0\0\0\1\6v\225\0\0\1\0\0\0\10\0\0\0\270v\16\0"..., 32768, 31916032) = 32768
5197  pread(258, "\6\242\0\0\363\26@\0\2544\0\0\0\0\2\4\36\202\0\0\1\0\0\0\10\0\0\0\2544\0\0"..., 24576, 48128000) = 24576
5197  pread(258, "\6\242\0\0\361\35@\0\353@\0\0\0\0\2\4\r\301\0\0\1\0\0\0\10\0\0\0\353@\0\0"..., 8192, 62791680) = 8192
5197  pread(258, "\6\242\0\0s5@\0\231@\3\0\0\0\3\4\211\305\0\0\1\0\6\0\10\0\0\0\231@\3\0"..., 8192, 112091136) = 8192
5197  pread(258, "\6\242\0\0u5@\0\255\266\1\0\0\0\1\6\215\221\0\0\1\0\0\0\10\0\0\0\237\266\1\0"..., 16384, 112107520) = 16384
5197  pread(258, "\6\242\0\0pm@\0\313\327\2\0\0\0\1\6\205_\0\0\1\0 \0\10\0\0\0x\327\2\0"..., 8192, 229507072) = 8192
5197  pread(258, "\6\242\0\0rm@\0\261\341\2\0\0\0\1\6\317}\0\0\1\0\24\0\10\0\0\0006\341\2\0"..., 8192, 229523456) = 8192
5197  pread(258, "\6\242\0\0\246!A\0r+\16\0\0\0\1\6F\323\0\0\1\0\33\0\10\0\0\0\274*\16\0"..., 8192, 607436800) = 8192
5197  pread(258, "\6\242\0\0\252!A\0\223\26\17\0\0\0\1\6s\322\0\0\1\0@\0\10\0\0\0\222\26\17\0"..., 8192, 607469568) = 8192
5197  pread(258, "\6\242\0\0\254!A\0\264m\16\0\0\0\2\4k\6\0\0\1\0@\0\10\0\0\0\264m\16\0"..., 40960, 607485952) = 40960
5197  pread(263, "#\242\0\0\202\0\200\1-\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 1064960) = 8192
5197  pread(263, "#\242\0\0\2\3\200\1v\320_\0\0\0\1\4\322\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 6307840) = 8192
5197  pread(263, "#\242\0\0\2\10\200\1\270\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 16793600) = 8192
5197  pread(258, "\6\242\0\0\265!A\0l\224\16\0\0\0\3\0040\324\0\0\1\0\0\0\10\0\0\0l\224\16\0"..., 16384, 607559680) = 16384
5197  pread(263, "#\242\0\0\202\0\200\1-\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 1064960) = 8192
5197  pread(258, "\6\242\0\0\36\v@\0\244\"\3\0\0\0\1\6\322\333\0\0\1\0\0\0\274\1\0\0\241\"\3\0"..., 8192, 23314432) = 8192
5197  pread(258, "\6\242\0\0\37\v@\0\244\"\3\0\0\0\1\6A\301\0\0\1\0\0\0\274\1\0\0\242\"\3\0"..., 8192, 23322624) = 8192
5197  pread(258, "\6\242\0\0\305\3@\0\2228\17\0\0\0\1\6\211+\0\0\2\0\0\0y\0\0\0\2168\17\0"..., 8192, 7905280) = 8192
5197  pread(258, "\6\242\0\0\253\3@\0\2228\17\0\0\0\1\6\375\316\0\0\1\0\36\0v\0\0\0\2168\17\0"..., 8192, 7692288) = 8192
5197  pread(263, "#\242\0\0\2\3\200\1v\320_\0\0\0\1\4\322\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 6307840) = 8192
5197  pread(263, "#\242\0\0\2\10\200\1\270\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 16793600) = 8192

--先分析263句柄的情况：
$ grep pread /tmp/map.txt | grep '263,'
5197  pread(263, "#\242\0\0\202\0\200\1-\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 1064960) = 8192
5197  pread(263, "#\242\0\0\2\3\200\1v\320_\0\0\0\1\4\322\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 6307840) = 8192
5197  pread(263, "#\242\0\0\2\10\200\1\270\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 16793600) = 8192
5197  pread(263, "#\242\0\0\202\0\200\1-\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 1064960) = 8192
5197  pread(263, "#\242\0\0\2\3\200\1v\320_\0\0\0\1\4\322\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 6307840) = 8192
5197  pread(263, "#\242\0\0\2\10\200\1\270\320_\0\0\0\1\4\321\361\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192, 16793600) = 8192

--1064960/8192=130
--6307840/8192=770
--16793600/8192=2050

SYS@book> select segment_name,header_file,header_block from dba_segments where owner='SCOTT' and header_file=6;
SEGMENT_NAME         HEADER_FILE HEADER_BLOCK
-------------------- ----------- ------------
T3                             6         2050
T2                             6          770
T1                             6          130

--正好是表T1,T2,T3的块头。也就是通过扫描表头，确定那些段使用了，回填位图区的信息。

5.做一个极端测试:

SYS@book> execute dbms_space_admin.TABLESPACE_REBUILD_BITMAPS('SUGAR');
PL/SQL procedure successfully completed.

SYS@book> shutdown abort
ORACLE instance shut down.

$ bvi -b 24576 -s 8192 /mnt/ramdisk/book/sugar01.dbf
00006000  1E A2 00 00 03 00 80 01 32 F5 5F 00 00 00 02 04 44 41 00 00 06 00 00 00 80 00 00 00 00 00 00 00 ........2._.....DA..............
00006020  00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF ................................
00006040  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006060  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006080  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060A0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060C0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060E0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................

--可以发现是FF。然后重新启动数据库到mount状态。

SYS@book> startup mount
ORACLE instance started.

Total System Global Area  634732544 bytes
Fixed Size                  2255792 bytes
Variable Size             197133392 bytes
Database Buffers          427819008 bytes
Redo Buffers                7524352 bytes
Database mounted.

RMAN> backup datafile 6 format '/u01/backup/d6_1.bak' ;
Starting backup at 2016-11-11 11:11:08
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=1 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00006 name=/mnt/ramdisk/book/sugar01.dbf
channel ORA_DISK_1: starting piece 1 at 2016-11-11 11:11:09
channel ORA_DISK_1: finished piece 1 at 2016-11-11 11:11:10
piece handle=/u01/backup/d6_1.bak tag=TAG20161111T111109 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 2016-11-11 11:11:10

$ ls -l /u01/backup/d6_1.bak
-rw-r----- 1 oracle oinstall 26066944 2016-11-11 11:11:09 /u01/backup/d6_1.bak

$ ls -lh /u01/backup/d6_1.bak
-rw-r----- 1 oracle oinstall 25M 2016-11-11 11:11:09 /u01/backup/d6_1.bak

--大小26066944/1024/1024=24.859375M,可以发现备份并不依赖这个位图区扫描。

SYS@book> alter database open ;
Database altered.

SYS@book> @ &r/bh 6 3
HLADDR              DBARFIL     DBABLK      CLASS CLASS_TYPE         STATE             TCH CR_SCN_BAS CR_SCN_WRP CR_UBA_FIL CR_UBA_BLK CR_UBA_SEQ BA               OBJECT_NAME
---------------- ---------- ---------- ---------- ------------------ ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------- --------------------
0000000084B84748          6          3         12 bitmap index block xcur                0          0          0          0          0          0 000000007A3C4000

SYS@book> alter system checkpoint;
System altered.

00006000  1E A2 00 00 03 00 80 01 32 F5 5F 00 00 00 02 04 44 41 00 00 06 00 00 00 80 00 00 00 00 00 00 00 ........2._.....DA..............
00006020  00 F8 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF FF FF ................................
00006040  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006060  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
00006080  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060A0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060C0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
000060E0  FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF ................................
--可以发现并没有修复位图区。

SYS@book> alter system checkpoint;
System altered.

SYS@book> oradebug setmypid
Statement processed.

SYS@book> oradebug peek 0x000000007A3C4100 16
[07A3C4100, 07A3C4110) = FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF

--从这里看也可以证明没有修复。

SCOTT@book> create table t4 tablespace sugar as select rownum id ,lpad('D',32,'D') name from dual connect by level<=1e5;
create table t4 tablespace sugar as select rownum id ,lpad('D',32,'D') name from dual connect by level<=1e5
                                                                                 *
ERROR at line 1:
ORA-00600: internal error code, arguments: [ktfbbssearch-9], [0], [624], [63488], [], [], [], [], [], [], [], []

--建表发现错误。

SYS@book> execute dbms_space_admin.TABLESPACE_REBUILD_BITMAPS('SUGAR');
PL/SQL procedure successfully completed.

SCOTT@book> create table t4 tablespace sugar as select rownum id ,lpad('D',32,'D') name from dual connect by level<=1e5;
Table created.

--OK，现在建表成功。

SCOTT@book> column PARTITION_NAME noprint
SCOTT@book> select * from dba_extents where owner=user and segment_name in ('T3','T4');
OWNER  SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME  EXTENT_ID    FILE_ID   BLOCK_ID      BYTES     BLOCKS RELATIVE_FNO
------ ------------ ------------ --------------- ---------- ---------- ---------- ---------- ---------- ------------
SCOTT  T3           TABLE        SUGAR                    0          6       2048      65536          8            6
SCOTT  T3           TABLE        SUGAR                    1          6       2056      65536          8            6
....
SCOTT  T3           TABLE        SUGAR                   21          6       2816    1048576        128            6
SCOTT  T3           TABLE        SUGAR                   22          6       2944    1048576        128            6
SCOTT  T3           TABLE        SUGAR                   23          6       3072    1048576        128            6
SCOTT  T3           TABLE        SUGAR                   24          6       3200    1048576        128            6
SCOTT  T4           TABLE        SUGAR                    0          6       3328      65536          8            6
...
SCOTT  T4           TABLE        SUGAR                   17          6       3584    1048576        128            6
SCOTT  T4           TABLE        SUGAR                   18          6       3712    1048576        128            6
SCOTT  T4           TABLE        SUGAR                   19          6       3840    1048576        128            6
45 rows selected.

--t3,T4的空间是连续的。

--看来做后台数据维护最大的敌人是死机或者掉电。

来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/267265/viewspace-2128290/，如需转载，请注明出处，否则将追究法律责任。

转载于:http://blog.itpub.net/267265/viewspace-2128290/

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Overwrite? (y/n) "); int c = getchar(); if (tolower(c) != 'y') { while ((c = getchar()) != '\n' && c != EOF); return; } remove_child(state->current_dir, filename); } int block = find_free_block(state); if (block == -1) { printf("No free disk space\n"); return; } FileNode* new_file = create_node(filename, FILE_TYPE); if (!new_file) { state->mfd.bitmap[block / 8] &= ~(1 << (block % 8)); printf("Memory allocation failed\n"); return; } new_file->start_block = block; new_file->size = BLOCK_SIZE; add_child(state->current_dir, new_file); printf("Created file: %s (block %d)\n", filename, block); } void delfile_command(SystemState* state, const char* filename) { if (!filename || *filename == '\0') { printf("Usage: delfile <filename>\n"); return; } FileNode* target = find_child(state->current_dir, filename); if (!target) { printf("File not found: %s\n", filename); return; } if (target->type != FILE_TYPE) { printf("Not a file: %s\n", filename); return; } if (target->start_block != -1) { state->mfd.bitmap[target->start_block / 8] &= ~(1 << (target->start_block % 8)); } remove_child(state->current_dir, filename); printf("Deleted file: %s\n", filename); } /********************* * 主程序 *********************/ int main() { SystemState state = {0}; init_filesystem(&state); char input[MAX_CMD_LEN]; char cmd[MAX_NAME_LEN]; char arg[MAX_NAME_LEN]; show_help(); while (true) { printf("\n%s:%s> ", state.current_user, state.current_dir->name); if (!fgets(input, MAX_CMD_LEN, stdin)) break; int args = sscanf(input, "%255s %255s", cmd, arg); if (args == 0) continue; if (strcmp(cmd, "login") == 0) { printf(login(&state) ? "Login successful\n" : "Login failed\n"); } else if (strcmp(cmd, "cd") == 0) { cd_command(&state, args >= 2 ? arg : NULL); } else if (strcmp(cmd, "dir") == 0) { dir_command(&state, args >= 2 ? arg : NULL); } else if (strcmp(cmd, "mkdir") == 0 && args >= 2) { mkdir_command(&state, arg); } else if (strcmp(cmd, "rmdir") == 0 && args >= 2) { rmdir_command(&state, arg); } else if (strcmp(cmd, "edit") == 0 && args >= 2) { edit_command(&state, arg); } else if (strcmp(cmd, "delfile") == 0 && args >= 2) { delfile_command(&state, arg); } else if (strcmp(cmd, "exit") == 0) { printf("Exiting system...\n"); break; } else { printf("Unknown command: %s\n", cmd); show_help(); } } cleanup_filesystem(&state); return 0; } void show_help(void) { printf("\nAvailable commands:\n"); printf("login - User login\n"); printf("cd [path] - Change directory\n"); printf("dir [path] - List directory contents\n"); printf("mkdir <dir> - Create directory\n"); printf("rmdir <dir> - Remove empty directory\n"); printf("edit <file> - Create/edit file\n"); printf("delfile <file> - Delete file\n"); printf("exit - Exit system\n"); } main函数中调用了cd_command和dir_command，且之前声明过这两个函数，但是没有提供这两个函数的实际实现，帮我实现这两个函数。给出修改后的代码
05-28
FileNode* find_parent(FileNode* node, FileNode* target) { for (int j = 0; j < node->child_count; j++) { if (node->children[j] == target) return node; FileNode* found = find_parent(node->children[j...
802.11N blockACK
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802.11n最主要的添加了Block Ack这个技术，但是在实际应用中对于BA还是知之甚少，转贴一个讲述BA基本原理的文章，但是我通过wireshark进行抓报并没有在BAR(Block Ack Requst)里面找到文中所说的相关信息，但是找到了一个CACE Technlologies 发布的一个用wireshark进行分析11n的文章，其内容请参见我的博客中另一篇有关文章。 以...
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