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Re: [Xen-users] Frequent para (Linux) domU hangs

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Subject: Re: [Xen-users] Frequent para (Linux) domU hangs
From: Ady Deac <ady@xxxxxxxxxxx>
Date: Sun, 20 Sep 2009 11:52:07 +0300
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Hi Jan,

You should strongly consider adding swap. Running a webserver is like running on ice. I am building custom servers for quite a long time, but I never ever considered that a web server has "sufficient" memory. Maybe only if we are talking about some 200-400GB RAM host? Then you could assign "sufficient" memory to each of your two web server and have some for the other 3 VPSs running there. Adding a 1GB swap file to each of your VPS will show that I'm right. ;) I always am! :D

Good luck!

Jan Bakuwel wrote:

I'm running Debian Lenny (2.6.26-1-xen-amd64) dom0 thats running 5
Debian Lenny 2.6.26-1-xen-amd64 domU's. The two busiest of those VMs
(webservers) frequently hang (every few days); the other three VMs have
not hung a single time in 122 days (and nor has dom0 obviously). The
syslogs (of the VMs and dom0) don't show anything useful; I haven't been
able to correlate the hangs with any event in particular; the hangs seem
to happen quite randomly (and not necessarily when the VMs are busy).
All domU's run without swap and sufficient memory (monitor statistics
show a fair bit of memory allocated to the cache at all times). All VMs
and dom0 share a single Internet connection and all run their own
specific firewall.

When a VM hangs, xentop actually thinks its running (its state = r and
its using nearly 100% CPU). Its not possible to connect to the VM via
the network (not even ping it), nor is it possible to connect the
console (console just hangs).

I appreciate any hints, suggestions, etc how I can further diagnose this


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Deac Mihai-Adrian

W: www.mikesoftware.com
P: +40-745-256.364

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