On Wed Nov 18, 2009 at 02:38:03PM +0100, Erwan MAS wrote: > Hello , > > I use md rai10 in 3 configurations : > - with 2 devices in f2 layout > - with 3 devices in f2 layout > - with 4 devices in f2 layout > > With the help of ( http://en.wikipedia.org/wiki/Non-standard_RAID_levels#Linux_MD_RAID_10 ) , > i had validated the layout for 2 / 3 devices . > Aka i read the block on the md device an i compare to each block on each physical devices . > > With my configuration with 4 devices , the comparaison does not work . > > Can someone explain me how to calculate the position of each chunk ? > > > My output of my md device : > > /dev/md2: > Version : 00.90.03 > Creation Time : Sun Jul 5 17:08:11 2009 > Raid Level : raid10 > Array Size : 527348736 (502.92 GiB 540.01 GB) > Used Dev Size : 263674624 (251.46 GiB 270.00 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 2 > Persistence : Superblock is persistent > > Update Time : Wed Nov 18 14:35:41 2009 > State : clean > Active Devices : 4 > Working Devices : 4 > Failed Devices : 0 > Spare Devices : 0 > > Layout : near=1, far=2 > Chunk Size : 256K > > UUID : e383a648:2d866213:bef1cd83:48bb11be > Events : 0.7603331 > > Number Major Minor RaidDevice State > 0 8 3 0 active sync /dev/sda3 > 1 8 35 1 active sync /dev/sdc3 > 2 8 19 2 active sync /dev/sdb3 > 3 8 51 3 active sync /dev/sdd3 > My understanding is that the layout should be (using your ordering): A C B D 1 2 3 4 5 6 7 8 . . . . . . . . 4 1 2 3 8 5 6 7 . . . . . . . . Allowing the loss of A & B, or C & D. Is this not what you're seeing on-disk? Cheers, Robin -- ___ ( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> | / / ) | Little Jim says .... | // !! | "He fallen in de water !!" |
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