On Sunday September 20, clintonlee.taylor@xxxxxxxxx wrote: > Greetings ... > > 2009/9/18 Majed B. <majedb@xxxxxxxxx>: > > For what it's worth, I use XFS on one of my arrays, and whenever > > mounting it, I get this error: > > > > [ 2212.567725] Filesystem "dm-0": Disabling barriers, trial barrier write failed > > > > So I guess you could use XFS to run your tests. > I saw this meesage today, and remember both this thread and that on > my CentOS 5.4, which I have moved a RAID5/ext4 filesystem from a > Fedora 10 ... > > I'm getting these reports in my message log ... > > Sep 19 14:59:52 zeus kernel: JBD: barrier-based sync failed on md5 - > disabling barriers > Sep 19 15:06:12 zeus kernel: EXT4-fs: barriers enabled > > Would this help with testing? Yes. There are a number of questions that broad testing testing could help answer. - is the performance impact of this barrier support inline with the performance impact of enabling barriers on a single device? - are there any unexpected interaction - e.g. does the array ever appear to lock up, either indefinitely or for an extended period of time due to usage of barriers? - does this barrier support result in a correct ordering of requests to media? i.e. is it actually doing what I mean it to do. The first two can be tested by regular use of any barrier-enabled file-system on top of an md array with these patches applied. The third really requires much more elaborate tests involving randomly powering off the system and then checking the filesystem for the sort of inconsistencies that barriers aim to prevent. So yes, running ext4 (or XFS or ext3 with barriers enabled) on an md array with barrier support added would help in testing the first two. I have rebased the relevant patches against 2.6.31 to make it easier to test them in a clean environment - testing a current 2.6.32-git would be too likely to result in unrelated problems. So pull from git://neil.brown.name/md barriers to get v2.6.31 plus md barrier support, or download and apply http://neil.brown.name/git?p=md;a=commitdiff_plain;h=fdc57f371ba0e3c8ce1ac9c0c4586829141531f3 http://neil.brown.name/git?p=md;a=commitdiff_plain;h=3467e61067ccd529e4b27b860a2d6cb29ea80766 Thanks, NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
