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dbcc checkdb

query for database gives errors. What is it, is it dangerous and how to resolve?

Full log file: download file or view on github (errors begin from string 364)

Possible There was disk d:\ crash before (there are .mdf and .ldf files on d:\Data). Disk was restored from backup. But not sure if these errors are related with this hardware crash.

DBCC results for 'DocStreams'. Msg 8914, Level 16, State 1, Line 1 Incorrect PFS free space information for page (1:103151) in object ID 1993058136, index ID 1, partition ID 72057594434682880, alloc unit ID 71906736119218176 (type LOB data). Expected value 0_PCT_FULL, actual value 100_PCT_FULL. Msg 8914, Level 16, State 1, Line 1 Incorrect PFS free space information for page (1:103887) in object ID 1993058136, index ID 1, partition ID 72057594434682880, alloc unit ID 71906736119218176 (type LOB data). Expected value 0_PCT_FULL, actual value 100_PCT_FULL. Msg 8914, Level 16, State 1, Line 1 Incorrect PFS free space information for page (1:104839) in object ID 1993058136, index ID 1, partition ID 72057594434682880, alloc unit ID 71906736119218176 (type LOB data). Expected value 0_PCT_FULL, actual value 100_PCT_FULL.

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    You potentially need to patch your database server (ref) as you could be running into a bug with the free-space tracking algorithm. This will hopefully resolve the issue going forward. To fix the error itself, try rebuilding the clustered index on the DocStreams table. – John Eisbrener Oct 14 '16 at 14:25
  • And Yes You are right, it could be just bug: "as long as the message tells you that the page is supposed to be empty, but is actually marked 100%, nothing can really go wrong with that page. Unfortunately, DBCC will keep reporting these errors." from Your link – Gennady G Oct 14 '16 at 16:23
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Thank You for response John!

Tried to backup DB and rebuild clustered index, but didn't help. As I understand there is no patch, but it is and old bug. Or something was really damaged during hardware crash..

This helped:

--dbcc checkdb;
--dbcc checktable(DocStreams) WITH ALL_ERRORMSGS;

ALTER DATABASE WSS_Content
SET SINGLE_USER WITH ROLLBACK IMMEDIATE

dbcc checktable(DocStreams, REPAIR_FAST) WITH ALL_ERRORMSGS;
GO
dbcc checktable(DocStreams, REPAIR_REBUILD) WITH ALL_ERRORMSGS;

-- use this only if above does not work
--DBCC CHECKTABLE(DocStreams, REPAIR_ALLOW_DATA_LOSS) WITH ALL_ERRORMSGS;

ALTER DATABASE WSS_Content SET MULTI_USER;

But first

  • Do backup database
  • I also backuped table using this cmd (press Enter multiple times):

    bcp WSS_Content.dbo.DocStreams out C:\backups\DocStreams\DocStreams.dat -t -T

    pause

Use in Your own risk)

links: incorrect-pfs bcp tool

Upd.: or You can try "reorganize with (lob_compaction = on)" first (link)

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