dd操作数据文件 – Database SOS

dd操作数据文件

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标题：dd操作数据文件

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

1.dd主要参数

       Copy a file, converting and formatting according to the operands.
       bs=BYTES
              force ibs=BYTES and obs=BYTES
       cbs=BYTES
              convert BYTES bytes at a time
       count=BLOCKS
              copy only BLOCKS input blocks
       ibs=BYTES
              read BYTES bytes at a time
       if=FILE
              read from FILE instead of stdin
       obs=BYTES
              write BYTES bytes at a time
       of=FILE
              write to FILE instead of stdout
       seek=BLOCKS
              skip BLOCKS obs-sized blocks at start of output
       skip=BLOCKS
              skip BLOCKS ibs-sized blocks at start of input

2.拷贝数据文件头部

[oracle@node1 chf]$ dd if=system01.dbf of=/tmp/dd_xifenfei01.dbf bs=8192 count=1
1+0 records in
1+0 records out
8192 bytes (8.2 kB) copied, 6.2e-05 seconds, 132 MB/s
[oracle@node1 chf]$ ll /tmp/dd_xifenfei01.dbf
-rw-r--r-- 1 oracle oinstall 8192 01-13 16:49 /tmp/dd_xifenfei01.dbf
BBED> set filename '/tmp/dd_xifenfei01.dbf'
        FILENAME        /tmp/dd_xifenfei01.dbf
BBED> set block 1
        BLOCK#          1
BBED> dump
 File: ././dd_xifenfei01.dbf (0)
 Block: 1                Offsets:    0 to  511           Dba:0x00000000
------------------------------------------------------------------------
 00a20000 0000c0ff 00000000 00000000 64590000 00200000 00a30200 7d7c7b7a
 a0810000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 <32 bytes per line>
BBED> set block 2
BBED-00309: out of range block number (2)
BBED> set offset 8190
        OFFSET          8190
BBED> dump
 File: ././dd_xifenfei01.dbf (0)
 Block: 1                Offsets: 8190 to 8191           Dba:0x00000000
------------------------------------------------------------------------
 0000
 <32 bytes per line>
--证明只有1个数据块(8192),并且拷贝数据文件头部成功

3.模拟创建文件

[oracle@node1 tmp]$ ll /tmp/dd_xifenfei02.dbf -h
-rw-r--r-- 1 oracle oinstall 1.0G 01-13 16:58 /tmp/dd_xifenfei02.dbf

4.拷贝数据块到一个文件中

[oracle@node1 chf]$ dd if=/tmp/dd_xifenfei01.dbf of=/tmp/dd_xifenfei02.dbf bs=8192 count=1
1+0 records in
1+0 records out
8192 bytes (8.2 kB) copied, 6e-05 seconds, 137 MB/s
[oracle@node1 chf]$ bbed
Password:
BBED: Release 2.0.0.0.0 - Limited Production on Fri Jan 13 17:01:02 2012
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
************* !!! For Oracle Internal Use only !!! ***************
BBED> set filename '/tmp/dd_xifenfei02.dbf'
BBED> set block 1
        BLOCK#          1
BBED> dump
 File: ././dd_xifenfei02.dbf (0)
 Block: 1                Offsets:    0 to  511           Dba:0x00000000
------------------------------------------------------------------------
 00a20000 0000c0ff 00000000 00000000 64590000 00200000 00a30200 7d7c7b7a
 a0810000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 <32 bytes per line>
BBED> set block 2
BBED-00309: out of range block number (2)
BBED> set offset 8190
        OFFSET          8190
BBED> dump
 File: ././dd_xifenfei02.dbf (0)
 Block: 1                Offsets: 8190 to 8191           Dba:0x00000000
------------------------------------------------------------------------
 0000
 <32 bytes per line>

通过对比在2步骤中拷贝出来的数据文件头部，证明现在已经把该头部拷贝到了3步骤创建的新文件中

One thought on “dd操作数据文件”

惜分飞说道：

2012-07-24 16:12
dd拷贝一个小文件到大文件中,不truncate掉大文件中尾部多于部分类此语句
```
dd of=redo01.log  if=new_redo01.log bs=1024k count=10 seek=10 conv=notrunc
```
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