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@deepsoft.com wrote:

At Mon, 14 Feb 2011 20:13:31 +0200 CentOS mailing list centos@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@deepsoft.com Deepwoods Software        -- http://www.deepsoft.com/ ()  ascii ribbon campaign -- against html e-mail /\  www.asciiribbon.org   -- against proprietary attachments

---

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2011/2/14 compdoc compdoc@hotrodpc.com:

...

end_request: I/O error, dev sda, sector 451792231

You should run: smartctl -a /dev/sda

Look for something like this line:

Reallocated_Sector_Ct   0x0033 100  100 036 Pre-fail  Always - 0

If that last value is greater than 0, replace the drive...

Value is 0, on both drives.

-- Eero

2011/2/14 compdoc compdoc@hotrodpc.com:

...

Value is 0, on both drives.

It's still possible to have a bad sector, but not have it show up in the Reallocated Sector Count.

What does this line say:

Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0

Is the last value greater than zero?

last value is 0, on both drives.

-- Eero

2011/2/14 compdoc compdoc@hotrodpc.com:

...

last value is 0, on both drives.

Looks to me like Smart thinks the drives are fine. Are they over-heating?

Hard to say, system is about 4++ years old :)

What drives are they? Have a model number?

maybe it just wise to install new server..

-- Eero