Messages in this thread |  | | | Date | Wed, 02 Sep 2009 20:17:41 +0400 | | From | Michael Tokarev <> | | Subject | Re: MD/DM and barriers (was Re: [patch] ext2/3: document conditions when reliable operation is possible) |
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Pavel Machek wrote: > On Thu 2009-08-27 12:54:05, Jeff Garzik wrote: [] >> Only md/raid1 supports barriers at present, it seems. None of the other >> MD drivers support barriers. > > Not even md/raid0? Ouch :-(.
Only for raid1 there's no requiriment for inter-drive ordering. Hence only raid1 supports barriers (and gained that support very recently, in 1 or 2 kernel releases). For the rest, including raid0 and linear, inter-drive ordering is necessary to implement barriers. Or md should have its own queue (flushing) mechanisms.
/mjt
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