IBM 000-8697 Manuel d'utilisateur télécharger pdf (Page 385)

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Data Consistency, Recovery, and Migration 4-13

Recovering from Corruption

OnLine alerts the user and administrator to possible corruption through the

following means:

■ Errormessagesreportedtotheapplication statethatpages,tables,or

databases cannot be found. The following message:

-105 ISAM error: bad isam file format

is always returned to the application if an operation has failed

because of an inconsistency in the underlying data or control

information.

■ Consistency-checking messages are written to the OnLine message

log. The following message:

Fail Consistency Check

includes diagnostic information that can help you determine the

source of the problem.

■ The tbcheck utility returns errors.

Corrective actions for tbcheck errors are described, by tbcheck

option, beginning on page 4-6.

At the ﬁrst indication of corruption, run tbcheck -cI to determine if

corruptionexistsintheindex.Ifyouruntbcheck-cIinonlinemode,tbcheck

detects the corruption but does not prompt you for repairs. If corruption

exists, you can drop and re-create the indexes using SQL statements while

you are in online mode. If you run tbcheck -cI in quiescent mode and

corruption is detected, tbcheck prompts you to conﬁrm whether the utility

should attempt to repair the corruption.

If tbcheck reports bad key information in an index, drop the index and re-

create it.

If tbcheck is unable to ﬁnd or access the table or database, verify the UNIX

permissionsonthe device (chunk)wherethetableresides.Ifpermissionsare

not thesource of the problem, thechunk might be down. (Referto page 1-48

for more details about the proper device permissions.)

If an I/O error occurs during OnLine operation, the status of the chunk on

which the error occurred changes to down. If a chunk is down, the tbstat -d

display shows the chunk status as PD- for a primary chunk and MD- for a

mirror chunk. A message written to the OnLine message log contains the

UNIX error number that identiﬁes the cause of the I/O error.

1 2 ... 380 381 382 383 384 385 386 387 388 389 390 ... 701 702

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IBM 000-8697 Manuel d'utilisateur Page 385

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