<div dir="ltr"><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)">Hi,</span></span></span><br><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"></span></span></span><div class="gmail_quote"><div dir="ltr"><div><div><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><br></span></span></span></div><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)">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. <br><br><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">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:<br><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><code style="margin:2px 0px;padding:5px 0px 0px;border:0px none;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:0.9em;line-height:1.3em;vertical-align:baseline;overflow:auto;display:block;height:auto;max-height:200px;white-space:normal">virsh console <domain></code></span></span></span><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"></span></span></span></span><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">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!).</span><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">After a bit of research and digging around, we eventually found these 2 nuggets:</span><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"></span></span></span><a href="https://wiki.gentoo.org/wiki/Xen#Xen_domU_hanging_with_kernel_4.3.2B">https://wiki.gentoo.org/wiki/Xen#Xen_domU_hanging_with_kernel_4.3.2B</a><br><a href="https://www.novell.com/support/kb/doc.php?id=7018590">https://www.novell.com/support/kb/doc.php?id=7018590</a><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">They both advise adding the command line argument:</span></span></span></span><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none"><br><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><code style="margin:2px 0px;padding:5px 0px 0px;border:0px none;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:0.9em;line-height:1.3em;vertical-align:baseline;overflow:auto;display:block;height:auto;max-height:200px;white-space:normal">gnttab_max_frames=256</code></span></span></span>(the default is 32).<span> </span></span><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">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<span> </span></span></span></span></span><a href="https://bugs.centos.org/view.php?id=14258">https://bugs.centos.org/view.php?id=14258</a><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none"><span> </span>and<span> </span></span></span></span></span><a href="https://bugs.centos.org/view.php?id=14284">https://bugs.centos.org/view.php?id=14284</a><span style="font-family:tahoma,sans-serif"><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none"><span> </span>(which
 are essentially the same report). There hasn't really been any movement
 on these tickets unfortunately, but I have +1'd them. <br><br>Have any others had issues with Xen and DomU's locking up in CentOS 7?<span> </span></span>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).<br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">Any help would be much appreciated and would mean my Ops guys could get a decent sleep!</span><br style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><span style="font-size:13px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">Cheers</span><br></span></span></span></div><span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"><span style="font-family:tahoma,sans-serif">Darren</span><div class="gmail-yj6qo"></div><div class="gmail-adL"><br></div></span></span></div></div><br></div>