Good morning, I'm fairly new to CentOS and am experiencing this error. I am hoping someone can help me out or point me in the right direction. I'm learning about CentOS in school but recently came across this issue at the workplace. It runs our website and constantly needs to be rebooted every couple weeks when this error comes up.

sd 0:0:0:0: rejecting I/O to offline device

When this error occurs, we can not do anything except for restart the server. The problem is it is random. We narrowed it down to every 20 days or so. When this error happens, the web site is offline and customers can not place orders until we restart it. This is obviously a big problem.

Here is some information since I am not sure exactly what to look for:

Kernel and CPU Linux 2.6.32-279.22.1.el6.x86_64 on an x86_64
Processor information Intel(R) Xeon(R) CPU E5540 @ 2.53GHz, 2 cores

Running on: Windows 2008 R2 64 bit (36GB Ram), Hyper-V Manager
HP LOGICAL VOLUME SCSI Disk Device 850GB SCSI hdd
CentOS Linux 6.3

I looked through dmesg and found some things like this:

* Found PM-Timer Bug on the chipset. Due to workarounds for a bug,
* this clock source is slow. Consider trying other clock sources

sd 0:0:0:0: [sda] 209715200 512-byte logical blocks: (107 GB/100 GiB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 0f 00 10 00
sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, supports DPO and F
UA
sda: sda1 sda2
sd 0:0:0:0: [sda] Attached SCSI disk

I'm not sure what is important or not. If you need any additional information I can get that. Any input is appreciated.

Any chance you can do "yum update" to go to 6.5 or higher?

In RHEL 6.3 the Hyper-V support was add on you had to install after the OS. In 6.4 it was installed with the OS but it didn't necessarily load all the modules automatically (you could use modprobe to do so however). In 6.5 it seems to work out of the box on Hyper-V without tweaking. Since CentOS is a binary compile of RHEL source of the same version it means this should be true for CentOS as well.

For what its worth the modules for Hyper-V running on my RHEL6.5 system seen with lsmod command are:
hid_hyperv 4350 0
hv_netvsc 23702 0
hv_utils 9149 0
hyperv_fb 7769 2
hv_storvsc 11323 3
hv_vmbus 144850 5 hid_hyperv,hv_netvsc,hv_utils,hyperv_fb,hv_storvsc

hv_storsvc above is the Hyper-V storage driver. If not running you may be able to add it with modprobe (not sure if this was same name in the add on for 6.3 as I never did install the add on myself).

I got a lot of information from this link when I ran into issues a few months back:
http://social.technet.microsoft.com/...rationservices

Of course your initial message could be an indication the underlying disks in the Hyper-V hypervisor itself is an issue. Do you have other guests on this hypervisor? Do they have any issues? Have you checked the event logs on the hypervisor itself?

Thank you so much for the reply! I'll dig into the link you posted and also take a look at the event logs and modules loaded. I'll report back with what I find.