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Very strange guest network hang [message #33340]

Wed, 08 October 2008 11:15

pentarh
Messages: 13
Registered: October 2008
Location: Russia

Junior Member

I constantly observe very strange guests hanging on my host machine.

During few days after start, guest OS stops to respond to incoming connections (even SSH).

There is total silence in logs about this. I just notice that suddenly guest disappeared from network.

Then i login to host, and

host# vzctl status guest
VEID 100 exist mounted running

host# vzctl enter guest
entered into VE 100
-bash-3.2#

all commands working inside guest, but network is down. All processes excepting my shell are in sleep state.

/proc/user_beancounters shows 0 of any failcnt - no limits were reached.

The only thing helps - to stop and start guest.

This happens not only on one guest - there are three guests and all of them periodilcally have network hangs.

What is that?

==========My config============
Host OS: Centos 5.2 x86_64
Guests: from official OS templates: centos-5-i386-minimal, centos-5-x86_64-minimal
Host kernel: 2.6.18-92.1.1.el5.028stab057.2 #1 SMP

host# cat /proc/vz/version
028stab057
host# vzctl --version
vzctl version 3.0.22

Network configuration is standard venet. I use real IP addresses for guests. When creating guest, i remove IP alias from host and add it to guest. There are no firewalls used.

Example of guest config on x86_64:

ONBOOT="yes"

# UBC parameters (in form of barrier:limit)
KMEMSIZE="30372700:35372700"
LOCKEDPAGES="256:256"
PRIVVMPAGES="262144:262144"
SHMPAGES="21504:21504"
NUMPROC="512:512"
PHYSPAGES="0:9223372036854775807"
VMGUARPAGES="67584:9223372036854775807"
OOMGUARPAGES="26112:9223372036854775807"
NUMTCPSOCK="360:360"
NUMFLOCK="188:206"
NUMPTY="16:16"
NUMSIGINFO="256:256"
TCPSNDBUF="1720320:2703360"
TCPRCVBUF="1720320:2703360"
OTHERSOCKBUF="1126080:2097152"
DGRAMRCVBUF="262144:262144"
NUMOTHERSOCK="360:360"
DCACHESIZE="3409920:3624960"
NUMFILE="9312:9312"
AVNUMPROC="180:180"
NUMIPTENT="128:128"

# Disk quota parameters (in form of softlimit:hardlimit)
DISKSPACE="10485760:20971520"
DISKINODES="200000:220000"
QUOTATIME="0"

# CPU fair sheduler parameter
CPUUNITS="1000"

VE_ROOT="/vz/root/$VEID"
VE_PRIVATE="/vz/private/$VEID"
OSTEMPLATE="centos-5-x86_64-minimal"
ORIGIN_SAMPLE="vps.basic"
NAME="blogs"
IP_ADDRESS="x.x.x.x"
HOSTNAME="myguest.com"
NAMESERVER="y.y.y.y"

[Updated on: Wed, 08 October 2008 11:15]

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Re: Very strange guest network hang [message #33344 is a reply to message #33340]

Wed, 08 October 2008 12:13

maratrus
Messages: 1495
Registered: August 2007
Location: Moscow

Senior Member

Hello,

- check sysctl parameters
http://wiki.openvz.org/Quick_installation#sysctl
- check your routing table. It should contain "$VE_IP dev venet0 scope link" record
- check arp table "ar -n". it should contain something like this
"$VE_IP * * MP eth*"
- use tcpdump utility to find out if the packets deliver HN, do they appear inside venet0 interface on the HN, do they appear inside venet0 interface in VPS

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Re: Very strange guest network hang [message #33345 is a reply to message #33344]

Wed, 08 October 2008 12:49

pentarh
Messages: 13
Registered: October 2008
Location: Russia

Junior Member

my sysctls are:

net.ipv4.conf.default.accept_source_route = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
net.core.netdev_max_backlog = 8196
net.core.somaxconn = 1024

net.ipv4.ip_forward = 1
net.ipv4.conf.default.proxy_arp = 0
net.ipv4.conf.all.rp_filter = 1
kernel.sysrq = 1
net.ipv4.conf.default.send_redirects = 1
net.ipv4.conf.all.send_redirects = 0

routings are also ok as well as arp

Now all of VE functioning normally. But i expect in a few days their network will go down again in some reason Sad

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