解剖SQLSERVER 第十七篇使用 OrcaMDF Corruptor 故意损坏数据库（译）

http://improve.dk/corrupting-databases-purpose-using-orcamdf-corruptor/

有时候你必须先作恶，后行善。情况就是当你想磨练你的数据库修复技能

我现在添加了一个Corruptor 类到OrcaMDF里面去测试新的RawDatabase 的功能。Corruptor 就跟他的名字一样--他会故意损坏数据库文件

Corruptor 本身是比较简单的。Corruptor 会随机选择一些页面并且简单的使用0来完全复写页面。
根据页面的类型，这可能会造成致命伤害

我不想多说什么了，不过万一。。。请不要在你的生产库上运行。这会损坏你的数据。

例子
有两个 Corruptor.CorruptFile重载方法，他们都返回integers 的枚举值 -- 一系列的pageid 列表并且被复写0的

下面的代码会损坏5%的页面在AdventureWorks2008R2LT.mdf 文件里面，然后他会输出每个被损坏了的页面ID 。
你可以定义损坏页面的百分比只需要改变第二个参数

var corruptedPageIDs = Corruptor.CorruptFile(@"C:\AdventureWorks2008R2LT.mdf", 0.05);
Console.WriteLine(string.Join(", ", corruptedPageIDs));

606, 516, 603, 521, 613, 621, 118, 47, 173, 579,
323, 217, 358, 515, 615, 271, 176, 596, 417, 379,
269, 409, 558, 103, 8, 636, 200, 361, 60, 486,
366, 99, 87

为了使损坏更厉害，你也可以使用第二个重载方法，他允许你定义一个确切的损坏页面的数目，在一个确定的pageid范围内。
下面的代码会确切的损坏pageid在0到49这个范围内的10个页面，因此会损坏大部分的元数据，大家知道系统表的数据基本都存储在数据库最靠前的页面上

var corruptedPageIDs = Corruptor.CorruptFile(@"C:\AdventureWorks2008R2LT.mdf", 10, 0, 49);
Console.WriteLine(string.Join(", ", corruptedPageIDs));

16, 4, 0, 32, 15, 14, 30, 2, 49, 9

在上面的情况我非常不幸的看到下面这些页面都被填充了0 包括：

file header page，page 2 is the first GAM page，page 9 is the boot page ，page 16 allocation unit metadata。

这样的损坏程度，即使使用DBCC CHECKDB也没办法修复，留下给你的选择只有从备份中还原

或者，你可以尝试一下使用OrcaMDF RawDatabase去恢复尽可能多的数据，先到这里了，我以后还会继续介绍。

DBCC TRACEON(3604,-1)
GODBCC PAGE([sss],1,16,3)
GODBCC 执行完毕。如果 DBCC 输出了错误信息，请与系统管理员联系。PAGE: (1:16)BUFFER:BUF @0x0000000080FDEB80bpage = 0x0000000080A74000 bhash = 0x0000000000000000 bpageno = (1:16)
bdbid = 8 breferences = 0 bcputicks = 0
bsampleCount = 0 bUse1 = 19980 bstat = 0xc00009
blog = 0x32159 bnext = 0x0000000000000000PAGE HEADER:Page @0x0000000080A74000m_pageId = (1:16) m_headerVersion = 1 m_type = 1
m_typeFlagBits = 0x4 m_level = 0 m_flagBits = 0x200
m_objId (AllocUnitId.idObj) = 7 m_indexId (AllocUnitId.idInd) = 0 Metadata: AllocUnitId = 458752
Metadata: PartitionId = 458752 Metadata: IndexId = 1 Metadata: ObjectId = 7
m_prevPage = (0:0) m_nextPage = (1:130) pminlen = 73
m_slotCnt = 49 m_freeCnt = 4225 m_freeData = 4331
m_reservedCnt = 0 m_lsn = (1037:459:3) m_xactReserved = 0
m_xdesId = (0:455) m_ghostRecCnt = 0 m_tornBits = -563242027Allocation StatusGAM (1:2) = ALLOCATED SGAM (1:3) = NOT ALLOCATED
PFS (1:1) = 0x60 MIXED_EXT ALLOCATED 0_PCT_FULL DIFF (1:6) = CHANGED
ML (1:7) = NOT MIN_LOGGEDSlot 0 Offset 0x60 Length 77Record Type = PRIMARY_RECORD Record Attributes = NULL_BITMAP Record Size = 77Memory Dump @0x000000000DC7A0600000000000000000: 10004900 00000300 00000000 01000003 †..I.............
0000000000000010: 00000000 00000000 0001001f 00000001 †................
0000000000000020: 00570000 00010056 00000001 000b0000 †.W.....V........
0000000000000030: 00000000 00090000 00000000 00110000 †.....    ..........
0000000000000040: 00000000 00010000 000c0000 00††††††††.............Slot 0 Column 1 Offset 0x4 Length 8 Length (physical) 8auid = 196608Slot 0 Column 2 Offset 0xc Length 1 Length (physical) 1type = 1Slot 0 Column 3 Offset 0xd Length 8 Length (physical) 8ownerid = 196608Slot 0 Column 4 Offset 0x15 Length 4 Length (physical) 4status = 0Slot 0 Column 5 Offset 0x19 Length 2 Length (physical) 2fgid = 1pgfirst = [Binary data] Slot 0 Column 6 Offset 0x1b Length 6 Length (physical) 6pgfirst = 0x1f0000000100pgroot = [Binary data] Slot 0 Column 7 Offset 0x21 Length 6 Length (physical) 6pgroot = 0x570000000100pgfirstiam = [Binary data] Slot 0 Column 8 Offset 0x27 Length 6 Length (physical) 6pgfirstiam = 0x560000000100Slot 0 Column 9 Offset 0x2d Length 8 Length (physical) 8pcused = 11Slot 0 Column 10 Offset 0x35 Length 8 Length (physical) 8pcdata = 9Slot 0 Column 11 Offset 0x3d Length 8 Length (physical) 8pcreserved = 17Slot 0 Column 12 Offset 0x45 Length 4 Length (physical) 4dbfragid = 1Slot 0 Offset 0x0 Length 0 Length (physical) 0KeyHashValue = (016862d84319)

SELECT COUNT(*) FROM sys.[allocation_units]
--131
SELECT * FROM sys.[allocation_units]
SELECT * FROM sys.[system_internals_allocation_units]

存储在数据库1：16页面上（是[sys.system_internals_allocation_units]系统表）《深入解析sql2008》

第十七篇完

转载于:https://www.cnblogs.com/lyhabc/p/4027434.html