On 04/03/2012 08:43 AM, Phil Stracchino wrote:
>
> Stephen, by the way, if you're not already aware of it:  You probably
> want to set innodb_flush_log_at_trx_commit = 0.
>
> The default value of this setting is 1, which causes the log buffer to
> be written out to the lgo file and the logfile flushed to disk at every
> transaction commit.  (Which obviously has a performance impact.)  With a
> setting of 0, nothing is done at transaction commit, but the log buffer
> is written to the log file and the log file flushed to disk once per
> second.  There is a potential with this setting that up to the last full
> second of transactions can be list in the event of a mysqld crash, but
> ... if mysqld crashes in the middle of Bacula inserting attributes, that
> job is blown *anyway*, so there's really no loss.


This is an interesting suggestion.

I wonder if it's possible since I'm running the dump as a single 
transaction if my database is becoming unavailable during this flush, 
such that the 50 second timeout for the locks the jobs are requesting is 
surpassed.  I would expect writes to a database to require more flushing 
than read (i.e. a dump), but I wonder if this could explain the jobs 
failing at the tail-end of the dump.



>
> I also suggest innodb_autoinc_lock_mode = 2, which allows InnoDB to
> interleave auto_increment inserts.  This may possibly help with your
> locking problem.  Keep in mind though that if you use this setting and
> you have replication running, your binlog_format must be set to MIXED or
> ROW.
>
>


-- 
Stephen Thompson               Berkeley Seismological Laboratory
stephen AT seismo.berkeley DOT edu    215 McCone Hall # 4760
404.538.7077 (phone)           University of California, Berkeley
510.643.5811 (fax)             Berkeley, CA 94720-4760

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