I have centOS running on my server as of today it just began to become unresponsive at certain times and needs a reboot.It just locks up, and when I go /var/logs/messages all I see is this error, not sure if it has anything to do with the cause.

Aug 5 11:55:31 fastbox smartd[4477]: Device /dev/sdb not available
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sdc, opened
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sdc, IE (SMART) not enabled,
skip device Try 'smartctl -s on /dev/sdc' to turn on SMART features
Aug 5 11:55:31 fastbox smartd[4477]: Unable to register SCSI device /dev/sdc
at line 34 of file /etc/smartd.conf
Aug 5 11:55:31 fastbox smartd[4477]: Device /dev/sdc not available
Aug 5 11:55:31 fastbox smartd[4477]: Monitoring 0 ATA and 0 SCSI devices
Aug 5 11:55:31 fastbox smartd[4479]: smartd has fork()ed into background mode.

any help please?

What is output from
dmesg | grep -E "sd|smart"
grep smart /var/log*/messages | tail -50
grep -v "^#" `find /etc/ -name smartd.conf` |uniq
commands?

Or perhaps, you could resolve it yourself with a little help of our web search friendly machines like google.
http://lists.centos.org/pipermail/ce...st/063352.html

Sounds very much like your hard drives are timing out/becoming unresponsive.

I believe there were some 1 TB drives recently making headlines for having issues with linux environments; they would go into a "self scrub" cycle without providing a notification of sorts to the kernel, so the kernel either failed them out of a software RAID array, or could hard-lock if directly accessing the drive when it became unresponsive.

First things first I'd try enabling SMART on your SATA controllers in the motherboard BIOS, if these SATA ports are on the motherboard (and if you've not already done so).

Have you upgraded the system to a new kernel recently? If so, try booting the server into a previous kernel and see if there is a change for the better...

Good luck!

thanks for the reply, been using our age old friend google, but cant seem to solve it, as i may have mentioned, not sure if its really an issue, but those are the only errors that come up in logs , so I'm more inclined to believe that is what is causing my server to shutdown.

when I run your commands:
dmesg | grep -E "sd|smart"

Aug 5 08:49:46 fastbox smartd[4462]: smartd version 5.38 [x86_64-redhat-linux-g nu] Copyright (C) 2002-8 Bruce Allen
Aug 5 08:49:46 fastbox smartd[4462]: Home page is http://smartmontools.sourcefo rge.net/
Aug 5 08:49:46 fastbox smartd[4462]: Opened configuration file /etc/smartd.conf
Aug 5 08:49:46 fastbox smartd[4462]: Configuration file /etc/smartd.conf parsed .
Aug 5 08:49:46 fastbox smartd[4462]: Device: /dev/sda, opened
Aug 5 08:49:46 fastbox smartd[4462]: Device: /dev/sda, IE (SMART) not enabled, skip device Try 'smartctl -s on /dev/sda' to turn on SMART features
Aug 5 08:49:46 fastbox smartd[4462]: Unable to register SCSI device /dev/sda at line 32 of file /etc/smartd.conf
Aug 5 08:49:46 fastbox smartd[4462]: Device /dev/sda not available
Aug 5 08:49:46 fastbox smartd[4462]: Device: /dev/sdb, opened
Aug 5 08:49:46 fastbox smartd[4462]: Device: /dev/sdb, IE (SMART) not enabled, skip device Try 'smartctl -s on /dev/sdb' to turn on SMART features
Aug 5 08:49:46 fastbox smartd[4462]: Unable to register SCSI device /dev/sdb at line 33 of file /etc/smartd.conf
Aug 5 08:49:46 fastbox smartd[4462]: Device /dev/sdb not available
Aug 5 08:49:46 fastbox smartd[4462]: Device: /dev/sdc, opened
Aug 5 08:49:46 fastbox smartd[4462]: Device: /dev/sdc, IE (SMART) not enabled, skip device Try 'smartctl -s on /dev/sdc' to turn on SMART features
Aug 5 08:49:46 fastbox smartd[4462]: Unable to register SCSI device /dev/sdc at line 34 of file /etc/smartd.conf
Aug 5 08:49:46 fastbox smartd[4462]: Device /dev/sdc not available
Aug 5 08:49:46 fastbox smartd[4462]: Monitoring 0 ATA and 0 SCSI devices
Aug 5 08:49:46 fastbox smartd[4469]: smartd has fork()ed into background mode. New PID=4469.
Aug 5 11:55:31 fastbox smartd[4477]: smartd version 5.38 [x86_64-redhat-linux-g nu] Copyright (C) 2002-8 Bruce Allen
Aug 5 11:55:31 fastbox smartd[4477]: Home page is http://smartmontools.sourcefo rge.net/
Aug 5 11:55:31 fastbox smartd[4477]: Opened configuration file /etc/smartd.conf
Aug 5 11:55:31 fastbox smartd[4477]: Configuration file /etc/smartd.conf parsed .
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sda, opened
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sda, IE (SMART) not enabled, skip device Try 'smartctl -s on /dev/sda' to turn on SMART features
Aug 5 11:55:31 fastbox smartd[4477]: Unable to register SCSI device /dev/sda at line 32 of file /etc/smartd.conf
Aug 5 11:55:31 fastbox smartd[4477]: Device /dev/sda not available
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sdb, opened
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sdb, IE (SMART) not enabled, skip device Try 'smartctl -s on /dev/sdb' to turn on SMART features
Aug 5 11:55:31 fastbox smartd[4477]: Unable to register SCSI device /dev/sdb at line 33 of file /etc/smartd.conf
Aug 5 11:55:31 fastbox smartd[4477]: Device /dev/sdb not available
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sdc, opened
Aug 5 11:55:31 fastbox smartd[4477]: Device: /dev/sdc, IE (SMART) not enabled, skip device Try 'smartctl -s on /dev/sdc' to turn on SMART features
Aug 5 11:55:31 fastbox smartd[4477]: Unable to register SCSI device /dev/sdc at line 34 of file /etc/smartd.conf
Aug 5 11:55:31 fastbox smartd[4477]: Device /dev/sdc not available
Aug 5 11:55:31 fastbox smartd[4477]: Monitoring 0 ATA and 0 SCSI devices
Aug 5 11:55:31 fastbox smartd[4479]: smartd has fork()ed into background mode. New PID=4479.

ok cool stick, I will enable smartclt, I tried checking the raid for faulty disk but it doesnt work.

echo check > /sys/block/mdX/md/sync_action