take a closer look at the message it states: end_request: I/O error, dev sda, sector 451792263 this usually indicates there is corruption on the disk. the meaning is quite simple, you have a problem with your first disk /dev/sda , and you need to investigate it further. first of all run a smartctl --all /dev/sda look for FAIL messages, this will help indicate the cause of the I/O error. second step - to be sure its a bad disk ( sometimes it's not actually the disk ). check the cable connecting the disk , and replace it with a fresh one if available. also, i would recommend to check the power cable/supply this might cause I/O errors also. On Mon, Feb 14, 2011 at 8:39 PM, Robert Heller <heller at deepsoft.com> wrote: > At Mon, 14 Feb 2011 20:13:31 +0200 CentOS mailing list <centos at centos.org> wrote: > >> >> Hi List, >> >> What this means? >> >> md: syncing RAID array md0 >> md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc. >> md: using maximum available idle IO bandwidth (but not more than >> 200000 KB/sec) for reconstruction. >> md: using 128k window, over a total of 2096384 blocks. >> md: md0: sync done. >> RAID1 conf printout: >> --- wd:2 rd:2 >> disk 0, wo:0, o:1, dev:sda2 >> disk 1, wo:0, o:1, dev:sdb2 >> sd 0:0:0:0: SCSI error: return code = 0x06000000 >> end_request: I/O error, dev sda, sector 451792231 >> raid1: sda1: rescheduling sector 451792168 >> sd 0:0:0:0: SCSI error: return code = 0x06000000 >> end_request: I/O error, dev sda, sector 451792263 >> raid1: sda1: rescheduling sector 451792200 >> raid1: sdb1: redirecting sector 451792168 to another mirror >> raid1: sdb1: redirecting sector 451792200 to another mirror >> md: syncing RAID array md0 >> md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc. >> md: using maximum available idle IO bandwidth (but not more than >> 200000 KB/sec) for reconstruction. >> md: using 128k window, over a total of 2096384 blocks. >> md: md0: sync done. >> RAID1 conf printout: >> --- wd:2 rd:2 >> disk 0, wo:0, o:1, dev:sda2 >> disk 1, wo:0, o:1, dev:sdb2 >> >> note lines: >> >> sd 0:0:0:0: SCSI error: return code = 0x06000000 >> end_request: I/O error, dev sda, sector 451792263 >> raid1: sda1: rescheduling sector 451792200 >> raid1: sdb1: redirecting sector 451792168 to another mirror >> raid1: sdb1: redirecting sector 451792200 to another mirror >> >> Is one disk going down? cat /proc/mdstat still shows software raid >> array as working one. > > One disk is probably starting to fail. Are you getting SMART errors? > Have a look in /var/log/messages for smartd messages as well as kernel > I/O errors. > > -- > Robert Heller -- 978-544-6933 / heller at deepsoft.com > Deepwoods Software -- http://www.deepsoft.com/ > () ascii ribbon campaign -- against html e-mail > /\ www.asciiribbon.org -- against proprietary attachments > > > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > -- Best Regards, Yonatan Pingle RHCT | RHCSA | CCNA1