On Mon, Apr 30, 2018 at 1:08 PM, Daz Day dazday60@gmail.com wrote:
Hi,
I've tried hitting up the CentOS forums and thought I'd try here too as I don't seem to be getting any bites.
We've been in the process of migrating all our hypervisors over to CentOS 7 using Xen. Once we had a few up and running we started to notice that the DomU's would randomly freeze. They become unresponsive to any network traffic, stop consuming CPU resources on the hypervisor and it's not possible to log in to the console locally using: virsh console <domain> We can sometimes get as far as typing a username and hitting return, but the DomU just hangs there. It doesn't seem to matter what Linux distro the DomU is running, it affects them all. The only way we can get them back is by destroying and recreating them (far from ideal!).
After a bit of research and digging around, we eventually found these 2 nuggets: https://wiki.gentoo.org/wiki/Xen#Xen_domU_hanging_with_kernel_4.3.2B https://www.novell.com/support/kb/doc.php?id=7018590
They both advise adding the command line argument: gnttab_max_frames=256(the default is 32). We applied this change and all hypervisors rand stable for around a week until DomU's started freezing again (we've since tried even higher values, to no avail). More research later led me to https://bugs.centos.org/view.php?id=14258 and https://bugs.centos.org/view.php?id=14284 (which are essentially the same report). There hasn't really been any movement on these tickets unfortunately, but I have +1'd them.
Have any others had issues with Xen and DomU's locking up in CentOS 7? Are there any other fixes/workarounds? If any additional info is needed that isn't already in the bug tickets or forum post, please let me know and I'll be happy to provide whatever is required (these freezes are happening at least once a day).
Any help would be much appreciated and would mean my Ops guys could get a decent sleep! Cheers Darren
Darren,
Would you mind reposting this to xen-users, along with:
* The config file for your guests * The output of `dmesg` from inside one of the guests before it hangs * The output of `dmesg` run on your dom0 after one of these machine hangs
Thanks, -George