O_DIRECT warnings & can I trust "innobackupex: completed OK!" message?

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Oct 7, 2011, 11:23:38 AM10/7/11
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Good morning,

I have a gluster 3.2 filesystem I'm using for storage, mounted using the gluster native mount (as opposed to nfs) for performance, and I'm perfoming backups of a mysql-5.5.15-linux2.6-x86_64 server on Fedora release 10 with innobackupex (InnoDB Backup Utility v1.5.1-xtrabackup) as described in the Percona documentation. I get tons of these messages printed for both full backup and prepare stages:

111006 17:01:31 InnoDB: Failed to set O_DIRECT on file ./myPorkyDB/myPorkyTable.ibd: OPEN: Invalid argument, continuing anyway
111006 17:01:31 InnoDB: O_DIRECT is known to result in 'Invalid argument' on Linux on tmpfs, see MySQL Bug#26662

A little later on in each process I get:

111006 17:01:35 innobackupex: completed OK!

Does this mean that the backup succeeded irrespective of the messages regarding the failure to set O_DIRECT since it was able to complete the backup by "continuing anyway"?

Thank you for your time,

Steven Ayre

Oct 7, 2011, 11:41:53 AM10/7/11
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I'm a not one of the developers, but AFAIK the O_DIRECT is only to
disable caching the read data since the copy will not go back over
data it has already copied so it's better not to add it to the cache.
I don't think it'll cause a problem.


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Alexey Kopytov

Oct 11, 2011, 8:01:43 AM10/11/11
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Hi Xavier,

The message is more a warning than an error. Apparently O_DIRECT is not
supported by gluster. So InnoDB first tries to use it, and falls back to
a buffered IO if that fails.

So yes, you can ignore those messages.

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