I have three different types of CentOS 6 Xen 4.4 based hypervisors (by hardware) that are experiencing stability issues which I haven't been able to track down. All three types seem to be having issues with NIC and/or PCIe. In most cases, the issues are unrecoverable and require a hard boot to resolve. All have Intel NICs. Often the systems will remain stable for days or weeks, then suddenly encounter one of these issues. I have yet to tie the error to any specific action on the systems and can't reproduce it reliably. - Supermicro X8DT3, Dual Xeon E5620, 2x 82575EB NICs, 2x 82576 NICs Kernel messages upon failure: pcieport 0000:00:03.0: AER: Multiple Corrected error received: id=0018 pcieport 0000:00:03.0: PCIe Bus Error: severity=Corrected, type=Transaction Layer, id=0018(Receiver ID) pcieport 0000:00:03.0: device [8086:340a] error status/mask=00002000/00001001 pcieport 0000:00:03.0: [13] Advisory Non-Fatal pcieport 0000:00:03.0: Error of this Agent(0018) is reported first igb 0000:04:00.0: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=0400(Receiver ID) igb 0000:04:00.0: device [8086:10a7] error status/mask=00002001/00002000 igb 0000:04:00.0: [ 0] Receiver Error (First) igb 0000:04:00.1: PCIe Bus Error: severity=Corrected, type=Physical Layer, id=0401(Receiver ID) igb 0000:04:00.1: device [8086:10a7] error status/mask=00002001/00002000 igb 0000:04:00.1: [ 0] Receiver Error (First) This spams to the console continuously until hard booting. - Supermicro X9DRD-iF/LF, Dual Xeon E5-2630, 2x I350, 2x 82575EB igb 0000:82:00.0: Detected Tx Unit Hang Tx Queue <1> TDH <43> TDT <50> next_to_use <50> next_to_clean <43> buffer_info[next_to_clean] time_stamp <12e6bc0b6> next_to_watch <ffff880006aa7440> jiffies <12e6bc8dc> desc.status <1c8210> This spams to the console continuously until hard booting. - Supermicro X9DRT, Dual Xeon E5-2650, 2x I350, 2x 82571EB e1000e 0000:04:00.0 eth2: Detected Hardware Unit Hang: TDH <ff> TDT <33> next_to_use <33> next_to_clean <fd> buffer_info[next_to_clean]: time_stamp <138230862> next_to_watch <ff> jiffies <138231ac0> next_to_watch.status <0> MAC Status <80383> PHY Status <792d> PHY 1000BASE-T Status <3c00> PHY Extended Status <3000> PCI Status <10> This type of system, the NIC automatically recovers and I don't need to reboot. So far I tried using pcie_aspm=off to see that would help, but it appears that the 3.18 kernel turns off ASPM by default on these due to probing the BIOS. Stability issues were not resolved by the changes. On the latter system type I also turned off all offloading setting. It appears the stability increased slightly but it didn't fully resolve the problem. I haven't adjusted offload settings on the first two server types yet. I suspect this problem is related to the 3.18 kernel used by the virt SIG, as we had these running Xen on CentOS 5's kernel with no issues for years, and systems of these types used elsewhere in our facility are stable under CentOS 6's standard kernel. This affects more than one server of each type, so I don't believe it is a hardware failure, or else it's a hardware design flaw. Has anyone experienced similar issues with this configuration, and if so, does anyone have tips on how to resolve the issues? -- Kevin Stange Chief Technology Officer Steadfast | Managed Infrastructure, Datacenter and Cloud Services 800 S Wells, Suite 190 | Chicago, IL 60607 312.602.2689 X203 | Fax: 312.602.2688 kevin at steadfast.net | www.steadfast.net