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Torn page?

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Topic

jcbunn
Starting Member

1 Post

Posted - 2007-01-31 : 12:02:53

Hello,
I'm wondering if anyone has any insight as to what happened here. We had a DBCC checkdb error as follows:

Server: Msg 8946, Level 16, State 12, Line 2
Table error: Allocation page (16:3769008) has invalid PFS_PAGE page header values. Type is 0. Check type, object ID and page ID on the page.

So we then ran:
dbcc traceon(3604)
go
dbcc page (<dbname>,16,3769008,1,0)
go
dbcc traceoff(3604)
go

and got:
Server: Msg 8939, Level 16, State 98, Line 1
Table error: Object ID 99, index ID 0, page (16:3769008). Test (IS_ON (BUF_IOERR, bp->bstat) && bp->berrcode) failed. Values are 2057 and -1.

PAGE: (16:3769008)
------------------

BUFFER:
-------

BUF @0x00FE0640
---------------
bpage = 0x76F22000 bhash = 0x00000000 bpageno = (16:3769008)
bdbid = 6 breferences = 1 bstat = 0x809
bspin = 0 bnext = 0x00000000

PAGE HEADER:
------------

Page @0x76F22000
----------------
m_pageId = (16:3769008) m_headerVersion = 1 m_type = 11
m_typeFlagBits = 0x0 m_level = 0 m_flagBits = 0x0
m_objId = 99 m_indexId = 0 m_prevPage = (0:0)
m_nextPage = (0:0) pminlen = 0 m_slotCnt = 1
m_freeCnt = 2 m_freeData = 8188 m_reservedCnt = 0
m_lsn = (3975:179853:10) m_xactReserved = 0 m_xdesId = (0:0)
m_ghostRecCnt = 0 m_tornBits = 2

Allocation Status
-----------------
GAM (16:3578624) = NOT ALLOCATED
SGAM (16:3578625) = NOT ALLOCATED
PFS (16:3769008) = 0x0 0_PCT_FULL
DIFF (16:3578630) = NOT CHANGED
ML (16:3578631) = NOT MIN_LOGGED

DATA:
-----

Slot 0, Offset 0x4040
---------------------

Row at offset 16448 may be corrupt.
Hex dump of remaining -8258 bytes:

The database is not marked suspect and we have backups to restore, if necessary, but I'm wondering if anyone can interpret what the dbcc commands are telling us and how we can diagnosis what's happening...

Thanks!
Jason

paulrandal
Yak with Vast SQL Skills

899 Posts

Posted - 2007-01-31 : 12:26:26

You have header corruption in a PFS page (controls page allocations for approx 8000 data page). This means the page cannot be used and could cause problems if any of the pages that it controls have a change in their allocation status.

You can't repair this error through any means apart from restoring from your backups.

Please make sure you try to figure out what happened (check the SQL Server error log, the Windows Event log etc)

Thanks

Paul Randal
Principal Lead Program Manager, Microsoft SQL Server Core Storage Engine
(Legalese: This posting is provided "AS IS" with no warranties, and confers no rights.)
http://blogs.msdn.com/sqlserverstorageengine/default.aspx

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