On Tue, Oct 13, 2009 at 12:06:24PM +0100, mark delfman wrote: > A little more information which I ?think? seems to point at MD..... > > Creating an EXT3 FS on an MD RAID also shows a circa 50% performance drop. > We have tried a multitude of RAID options (raid6/0 various chunks etc). > > Using a hardware based raid XFS / EXT3 shows no performance drop > (although the hardware raid is significantly slower than MD in the > first place) > > We are happy to keep testing and offering anything that could be > useful, we are just a little stuck thinking of anything else to do.... Can you test with conv=direct added to the dd command lines? If that shows the problems too it's probably writeback-related. If not the problems must be somewhere lower in the stack. -- 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
