hi neil: I get your the latest patches (v2.6.29-rc5-335-g0ac4ee7) from git://neil.brown.name/md. I want to test the function that switch raid from raid5 to raid6. But find some problem. I create a raid6 which has 4 disks,and write some files to this raid6 ,next,i remove two of them. if this raid6 is ok,now i can read the files that i have written correctly. but in fact that i can't read the files ok.maybe there is some error about raid6 in v2.6.29-rc5-335-g0ac4ee7. Steps i have done are as follows 1, mdadm -C /dev/md6 -l 6 -n 4 /dev/sda /dev/sdb /dev/sdc /dev/sdd --metadata=1.0 --size=1000000 -f 2, pvcreate /dev/md6 3, vgcreate md6vg /dev/md6 4, lvcreate -L 200M -n md6lv md6vg 5, mkfs.xfs /dev/mapper/md6vg-md6lv 6, mount /dev/mapper/md6vg-md6lv /tmp (is ok) 7, mdadm -f /dev/md6 /dev/sda /dev/sdb (faulty two disks) 8, mount /dev/mapper/md6vg-md6lv /tmp (now can't read the filesystem information correctly) (mount: Structure needs cleaning) (print this ) thanks neil ,right here waiting for your help ! zhenchengjin ?韬{.n?????%??檩??w?{.n???{炳盯w???塄}?财??j:+v??????2??璀??摺?囤??z夸z罐?+?????w棹f