Re: mount - manual page does not list 'barrier' option for ext3 FS?
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On Tue, Aug 04, 2009 at 02:15:07AM +0300, Jari Aalto wrote: > > Manual page of mount(8), util-linux 2.15.1~rc1-1, reads > > Mount options for xfs > barrier > > Enables the use of block layer write barriers for writes > into the journal and unwritten extent conversion. This > allows for drive level write caching to be enabled, for > devices that support write barriers. > > <nothing more mentioned> This text is from official XFS documentation (Linux kernel, Documentation/filesystems/xfs.txt). (Unfortunately, filesystems documentation is still mess. It would be nice to have man page per filesystem and maintain all in kernel tree. This topic has been discussed more times, but.... Volunteers? ) > However in article: > > "Barriers and journaling filesystems" 2008-05-21 > http://lwn.net/Articles/283161/ > > ... ext3 and ext4 filesystems, by default, do not use barriers. The > option is there, but, unless the administrator has explicitly > requested the use of barriers, these filesystems operate without > them - though some distributions (notably SUSE) change that default. > ... > So barriers are disabled by default because they have a serious > impact on performance. And, beyond that, the fact is that people get > away with running their filesystems without using barriers. Reports > of ext3 filesystem corruption are few and far between. > > [Discussion] > ... > Posted May 21, 2008 14:17 UTC (Wed) by corbet (editor, #1) > Some quick grepping on my kernel tree disk suggests that ext3 got > the barrier option in 2.6.9. > > QUESTION > > Is the barrier option in the current 2.6.x kernels as mentioned? If it > is could someone document it to the manual page according to the > article. CC: too linux-xfs ML. Karel -- Karel Zak <kzak@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html