Sindbad~EG File Manager
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<p>
In some cases, the use of meta-data only journaling file
systems can lead to log file corruption. The window of
vulnerability is quite small, but if the operating system
experiences an unclean shutdown while Berkeley DB is creating
a new log file, it is possible that upon file system recovery,
the system will be in a state where the log file has been
created, but its own meta-data has not.
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<p>
When a log file is corrupted to this degree, normal
recovery can fail and your application may be unable to open
your environment. Instead, an error something like this is
issued when you attempt to run normal recovery on environment
open:
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<pre class="programlisting"> Ignoring log file: /var/dblog/log.0000000074: magic number
6c73732f, not 40988
Invalid log file: log.0000000074: Invalid argument
PANIC: Invalid argument
process-private: unable to find environment
txn_checkpoint interface requires an environment configured for
the transaction subsystem </pre>
<p>
In this case, it may be possible to successfully recover
the environment by ignoring the log file that was being
created — to do this, rename the log file with the
highest number to a temporary name:
</p>
<pre class="programlisting"> mv DBHOME/log.000000XXX my-temporary-log-file </pre>
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and try running normal environment recovery again. If
recovery is successful, and your application is able to open
the environment, then you can delete the log file that you
renamed.
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If recovery is not successful, then you must perform a
catastrophic recovery from a previous backup.
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This situation has been shown to occur when using ext3 in
writeback mode, but other journaling filesystems could exhibit
similar behavior.
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<p>
To be absolutely certain of your application's ability to
recover your environment in the event of a system crash,
either use non-journaling filesystems, or use a journaling
filesystem in a safe (albeit slower) configuration, such as
ext3 in ordered mode.
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Sindbad File Manager Version 1.0, Coded By Sindbad EG ~ The Terrorists