Ok, now put more files on your filesystem. I think you are correct and the buffer cache is handling the reads. > -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- > owner@xxxxxxxxxxxxxxx] On Behalf Of Patrik Jonsson > Sent: Sunday, May 15, 2005 4:55 PM > To: David Greaves; linux-raid@xxxxxxxxxxxxxxx > Subject: Re: Strange behaviour on "toy array" > > > > David Greaves wrote: > > > > >I think you'd need to post the commands you used and the results of > >things like mdadm --detail and cat /proc/mdstat > >also kernel version, mdadm version etc. > > > >That way we can ensure you really did fail the right drives etc etc. > > > >Right now it could be anything from (allowed!) user error to a weird ppc > >thing... > > > > > sure thing: > [root@localhost junk]# uname -a > Linux localhost.localdomain 2.6.9-prep #1 Tue Apr 19 16:00:33 PDT 2005 > ppc ppc ppc GNU/Linux > [root@localhost junk]# mdadm --version > mdadm - v1.6.0 - 4 June 2004 > > now I do (loop1-5 are files): > losetup /dev/loop0 loop1 > losetup /dev/loop1 loop2 > losetup /dev/loop2 loop3 > losetup /dev/loop3 loop4 > losetup /dev/loop4 loop5 > mdadm --create /dev/md0 -l 5 -n 5 /dev/loop0 /dev/loop1 /dev/loop2 > /dev/loop3 /dev/loop4 > mkfs.ext3 /dev/md0 > mount -t ext3 /dev/md0 junk > > at this point, mdadm shows: > [root@localhost junk]# mdadm --detail /dev/md0 > /dev/md0: > Version : 00.90.01 > Creation Time : Sun May 15 13:41:24 2005 > Raid Level : raid5 > Array Size : 3840 > Device Size : 960 > Raid Devices : 5 > Total Devices : 5 > Preferred Minor : 0 > Persistence : Superblock is persistent > > Update Time : Sun May 15 13:45:34 2005 > State : clean > Active Devices : 5 > Working Devices : 5 > Failed Devices : 0 > Spare Devices : 0 > > Layout : left-symmetric > Chunk Size : 64K > > Number Major Minor RaidDevice State > 0 7 0 0 active sync /dev/loop0 > 1 7 1 1 active sync /dev/loop1 > 2 7 2 2 active sync /dev/loop2 > 3 7 3 3 active sync /dev/loop3 > 4 7 4 4 active sync /dev/loop4 > UUID : b89aa5de:da1054f5:b052cc51:393d7435 > Events : 0.24 > > and /proc/mdstat: > [root@localhost junk]# cat /proc/mdstat > Personalities : [raid5] > md0 : active raid5 loop4[4] loop3[3] loop2[2] loop1[1] loop0[0] > 3840 blocks level 5, 64k chunk, algorithm 2 [5/5] [UUUUU] > > unused devices: <none> > > Now I fail (e.g.) /dev/loop0: > mdadm -f /dev/md0 /dev/loop0 > > and get: > [root@localhost junk]# mdadm --detail /dev/md0 > /dev/md0: > Version : 00.90.01 > Creation Time : Sun May 15 13:41:24 2005 > Raid Level : raid5 > Array Size : 3840 > Device Size : 960 > Raid Devices : 5 > Total Devices : 5 > Preferred Minor : 0 > Persistence : Superblock is persistent > > Update Time : Sun May 15 13:49:20 2005 > State : clean, degraded > Active Devices : 4 > Working Devices : 4 > Failed Devices : 1 > Spare Devices : 0 > > Layout : left-symmetric > Chunk Size : 64K > > Number Major Minor RaidDevice State > 0 0 0 -1 removed > 1 7 1 1 active sync /dev/loop1 > 2 7 2 2 active sync /dev/loop2 > 3 7 3 3 active sync /dev/loop3 > 4 7 4 4 active sync /dev/loop4 > 5 7 0 -1 faulty /dev/loop0 > UUID : b89aa5de:da1054f5:b052cc51:393d7435 > Events : 0.27 > > and: > [root@localhost junk]# cat /proc/mdstat > Personalities : [raid5] > md0 : active raid5 loop4[4] loop3[3] loop2[2] loop1[1] loop0[5](F) > 3840 blocks level 5, 64k chunk, algorithm 2 [5/4] [_UUUU] > > unused devices: <none> > > continue failing drives: > [root@localhost junk]# mdadm -f /dev/md0 /dev/loop1 > mdadm: set /dev/loop1 faulty in /dev/md0 > [root@localhost junk]# mdadm -f /dev/md0 /dev/loop2 > mdadm: set /dev/loop2 faulty in /dev/md0 > [root@localhost junk]# mdadm -f /dev/md0 /dev/loop3 > mdadm: set /dev/loop3 faulty in /dev/md0 > [root@localhost junk]# mdadm -f /dev/md0 /dev/loop4 > mdadm: set /dev/loop4 faulty in /dev/md0 > > now I get: > [root@localhost junk]# mdadm --detail /dev/md0 > /dev/md0: > Version : 00.90.01 > Creation Time : Sun May 15 13:41:24 2005 > Raid Level : raid5 > Array Size : 3840 > Device Size : 960 > Raid Devices : 5 > Total Devices : 5 > Preferred Minor : 0 > Persistence : Superblock is persistent > > Update Time : Sun May 15 13:51:09 2005 > State : clean, degraded > Active Devices : 0 > Working Devices : 0 > Failed Devices : 5 > Spare Devices : 0 > > Layout : left-symmetric > Chunk Size : 64K > > Number Major Minor RaidDevice State > 0 0 0 -1 removed > 1 0 0 -1 removed > 2 0 0 -1 removed > 3 0 0 -1 removed > 4 0 0 -1 removed > 5 7 4 -1 faulty /dev/loop4 > 6 7 3 -1 faulty /dev/loop3 > 7 7 2 -1 faulty /dev/loop2 > 8 7 1 -1 faulty /dev/loop1 > 9 7 0 -1 faulty /dev/loop0 > > and: > Personalities : [raid5] > md0 : active raid5 loop4[5](F) loop3[6](F) loop2[7](F) loop1[8](F) > loop0[9](F) > 3840 blocks level 5, 64k chunk, algorithm 2 [5/0] [_____] > > unused devices: <none> > > but I can still read the file on the filesystem that is mounted (ie in > the "junk" dir). > > Hope that contains all the info you need. > > /Patrik > > - 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