lvm volume resize by extending virtual disk image file

Below should be ran from Dom0 hosting DomU:

[root@Dom0 ~]# virt-filesystems -a System.img

[root@Dom0 ~]# virt-filesystems --long --parts --blkdevs -h -a System.img
Name Type MBR Size Parent
/dev/sda1 partition 83 500M /dev/sda
/dev/sda2 partition 8e 12G /dev/sda
/dev/sda device - 12G -

[root@Dom0 ~]# truncate -s 20G System_new.img

[root@Dom0 ~]# virt-resize --expand /dev/sda2 System.img System_new.img

[root@Dom0 ~]# mv System.img System.img.bak;mv System_new.img System.img

[root@Dom0 ~]# xm create vm.cfg -c #the first run may get issue "device cannot be connected", you can just run it again, the issue should be gone

Below should be ran from DomU:

[root@DomU ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vg01 1 2 0 wz--n- 20.51g 8.00g

[root@DomU ~]# lvextend -L +8g /dev/mapper/vg01-lv_root
[root@DomU ~]# resize2fs /dev/mapper/vg01-lv_root

[root@DomU ~]# df -h /
Filesystem Size Used Avail Use% Mounted on
20G 10G 10G 50% /

resolved - xend error: (98, 'Address already in use')

Today one OVS server met issue with ovs-agent and need reboot. As there were VMs running on it, so I tried live migrating xen based VMs using "xm migrate -l", but below error occurred:

-bash-3.2# xm migrate -l vm1 server1
Error: can't connect: (111, 'Connection refused')
Usage: xm migrate  

Migrate a domain to another machine.


-h, --help           Print this help.
-l, --live           Use live migration.
-p=portnum, --port=portnum
                     Use specified port for migration.
-n=nodenum, --node=nodenum
                     Use specified NUMA node on target.
-s, --ssl            Use ssl connection for migration.

As xen migration use xend-relocation-server of xend-relocation-port, so this "Connection refused" issue was most likely related to this. And below is the configuration of /etc/xen/xend-config.sxp:

-bash-3.2# egrep -v '^#|^$' /etc/xen/xend-config.sxp
(xend-unix-server yes)
(xend-relocation-server yes)
(xend-relocation-ssl-server no)
(xend-unix-path /var/lib/xend/xend-socket)
(xend-relocation-port 8002)
(xend-relocation-server-ssl-key-file /etc/ovs-agent/cert/key.pem)
(xend-relocation-server-ssl-cert-file /etc/ovs-agent/cert/certificate.pem)
(xend-relocation-address '')
(xend-relocation-hosts-allow '')
(vif-script vif-bridge)
(dom0-min-mem 0)
(enable-dom0-ballooning no)
(dom0-cpus 0)
(vnc-listen '')
(vncpasswd '')
(xend-domains-lock-path /opt/ovs-agent-2.3/utils/
(domain-shutdown-hook /opt/ovs-agent-2.3/utils/

And to check the progresses related with these:

-bash-3.2# lsof -i :8002
xend    12095 root    5u  IPv4 146473964       TCP *:teradataordbms (LISTEN)

-bash-3.2# ps auxww|egrep '/opt/ovs-agent-2.3/utils/|/opt/ovs-agent-2.3/utils/'
root  3501  0.0  0.0   3924   740 pts/0    S+   08:37   0:00 egrep /opt/ovs-agent-2.3/utils/|/opt/ovs-agent-2.3/utils/
root 19007  0.0  0.0  12660  5840 ?        D    03:44   0:00 python /opt/ovs-agent-2.3/utils/ --lock --name vm1 --uuid 56f17372-0a86-4446-8603-d82423c54367
root 27446  0.0  0.0  12664  5956 ?        D    05:11   0:00 python /opt/ovs-agent-2.3/utils/ --lock --name vm2 --uuid eb1a4e84-3572-4543-8b1d-685b856d98c7

When processes went into D state(uninterruptable sleep), it'll be troublesome, as these processes can only be killed by reboot the whole system. However, on this server, we had many VMs running, and now live migration/relocation was blocked by issue caused by itself, and deadlock surfaced. And seems reboot was the only way to "resolve" the issue.

Firstly, I tried bounce xend(/etc/init.d/xend restart), but met below error indicated in /var/log/message:

[2015-11-04 04:39:43 24026] INFO (SrvDaemon:227) Xend stopped due to signal 15.
[2015-11-04 04:39:43 24115] INFO (SrvDaemon:332) Xend Daemon started
[2015-11-04 04:39:43 24115] INFO (SrvDaemon:336) Xend changeset: unavailable.
[2015-11-04 04:40:14 24115] ERROR (SrvDaemon:349) Exception starting xend ((98, 'Address already in use'))
Traceback (most recent call last):
  File "/usr/lib/python2.4/site-packages/xen/xend/server/", line 339, in run
  File "/usr/lib/python2.4/site-packages/xen/xend/server/", line 159, in listenRelocation
    hosts_allow = hosts_allow)
  File "/usr/lib/python2.4/site-packages/xen/web/", line 36, in __init__
    connection.SocketListener.__init__(self, protocol_class)
  File "/usr/lib/python2.4/site-packages/xen/web/", line 89, in __init__
    self.sock = self.createSocket()
  File "/usr/lib/python2.4/site-packages/xen/web/", line 49, in createSocket
    sock.bind((self.interface, self.port))
  File "", line 1, in bind
error: (98, 'Address already in use')

And later, I realized that we can change xend-relocation-port to have a try. So I made below changes to /etc/xen/xend-config.sxp:

(xend-relocation-port 8003)

And later, bounced xend:

/etc/init.d/xend stop; /etc/init.d/xend start

PS: xend bouncing will not affect running VMs, as I had compared qemu output(ps -ef|grep qemu). A tip here is that when xen related commands(xm list, and so on) stopped working, checking for "qemu" simulator processes will help you get the VM list.

After this, "xm migrate -l vm1 server1" still failed with the same can't connect: (111, 'Connection refused'). And I resolved this by specifying port:(you may need stop iptables too):

-bash-3.2# xm migrate -l -p 8002 vm1 server1

Now the live migration went on smoothly, and after all VMs were migrated, I changed xend-relocation-port back to 8002 and reboot the server to fix the D state(uninterruptable sleep) issue.


If you find error "Error: can't connect: (111, 'Connection refused')" even after above WA, then you can change back from 8003 to 8002, or even from 8003 to 8004, restart iptables, and try again.

resolved - Error: Unable to connect to xend: Connection reset by peer. Is xend running?

Today I met some issue when trying to run xm commands on a XEN server:

[root@xenhost1 ~]# xm list
Error: Unable to connect to xend: Connection reset by peer. Is xend running?

I had a check, and found xend was actually running:

[root@xenhost1 ~]# /etc/init.d/xend status
xend daemon running (pid 8329)

After some debugging, I found it's caused by libvirtd & xend corrupted. And then I did a bounce of them:

[root@xenhost1 ~]# /etc/init.d/libvirtd restart
Stopping libvirtd daemon: [ OK ]
Starting libvirtd daemon: [ OK ]

[root@xenhost1 ~]# /etc/init.d/xend restart #this may not be needed 
restarting xend...
xend daemon running (pid 19684)

Later, the xm commands went good.


  • If you met issue like "resolved - xend error: (98, 'Address already in use')" when restart xend or "can't connect: (111, 'Connection refused')" when doing xm live migrate, then you can refer this article.
  • For more information about libvirt, you can check here.


resolved - cssh installation on linux server

ClusterSSH can be used if you need controls a number of xterm windows via a single graphical console window, and you want to run commands interactively on multiple servers over an ssh connection. This guide will show the process to install clusterssh on a linux box from tarball.

At the very first, you should download cssh tarball App-ClusterSSH-4.03_04.tar.gz from sourceforge. You may need export proxy settings if it's needed in your env:

export https_proxy=
export http_proxy=
export ftp_proxy=

After the proxy setting, you can now get the package:

wget ''
tar zxvf App-ClusterSSH-4.03_04.tar.gz
cd App-ClusterSSH-4.03_04

Before installing, let's install some prerequisites packages:

yum install gcc libX11-devel gnome* -y
yum groupinstall "X Window System" -y
yum groupinstall "GNOME Desktop Environment" -y
yum groupinstall "Graphical Internet" -y
yum groupinstall "Graphics" -y

Now run "perl Build.PL" as indicated by README:

[root@centos-32bits App-ClusterSSH-4.03_04]# perl Build.PL
Can't locate Module/ in @INC (@INC contains: /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/5.8.8/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.8 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.8/i386-linux-thread-multi /usr/lib/perl5/5.8.8 .) at Build.PL line 5.
BEGIN failed--compilation aborted at Build.PL line 5.

As it challenged, you need install first. Let's use cpan to install that module.

Run "cpan" and enter "follow" when below info occurred:

Policy on building prerequisites (follow, ask or ignore)? [ask] follow

If you had already ran cpan before, then you can configure the policy as below:

cpan> o conf prerequisites_policy follow
cpan> o conf commit

Now Let's install Module::Build:

cpan> install Module::Build

After the installation, let's run "perl Build.PL" again:

[root@centos-32bits App-ClusterSSH-4.03_04]# perl Build.PL
Checking prerequisites...
    !  Exception::Class is not installed
    !  Tk is not installed
    !  Try::Tiny is not installed
    !  X11::Protocol is not installed
    !  CPAN::Changes is not installed
    !  File::Slurp is not installed
    !  File::Which is not installed
    !  Readonly is not installed
    !  Test::Differences is not installed
    !  Test::DistManifest is not installed
    !  Test::PerlTidy is not installed
    !  Test::Pod is not installed
    !  Test::Pod::Coverage is not installed
    !  Test::Trap is not installed

ERRORS/WARNINGS FOUND IN PREREQUISITES.  You may wish to install the versions
of the modules indicated above before proceeding with this installation

Run 'Build installdeps' to install missing prerequisites.

Created MYMETA.yml and MYMETA.json
Creating new 'Build' script for 'App-ClusterSSH' version '4.03_04'

As the output says, run "./Build installdeps" to install the missing packages. Make sure you're in GUI env(through vncserver maybe), as "perl Build.PL" has a step to test GUI.

[root@centos-32bits App-ClusterSSH-4.03_04]# ./Build installdeps


Running Mkbootstrap for Tk::Xlib ()
chmod 644 ""
"/usr/bin/perl" "/usr/lib/perl5/5.8.8/ExtUtils/xsubpp" -typemap "/usr/lib/perl5/5.8.8/ExtUtils/typemap" -typemap "/root/.cpan/build/Tk-804.032/Tk/typemap" Xlib.xs > Xlib.xsc && mv Xlib.xsc Xlib.c
make[1]: *** No rule to make target `pTk/tkInt.h', needed by `Xlib.o'. Stop.
make[1]: Leaving directory `/root/.cpan/build/Tk-804.032/Xlib'
make: *** [subdirs] Error 2
/usr/bin/make -- NOT OK
Running make test
Can't test without successful make
Running make install
make had returned bad status, install seems impossible

Errors again, we can see it's complaining something about TK related thing. To resolve this, I manully installed the latest perl-tk module as below:

wget --no-check-certificate ''
unzip master
cd perl-tk-master
perl Makefile.PL
make install

After this, let's run "./Build installdeps" and "perl Build.PL" again which all went through good:

[root@centos-32bits App-ClusterSSH-4.03_04]# ./Build installdeps

[root@centos-32bits App-ClusterSSH-4.03_04]# perl Build.PL

And let's run ./Build now:

[root@centos-32bits App-ClusterSSH-4.03_04]# ./Build
Building App-ClusterSSH
Generating: ccon
Generating: crsh
Generating: cssh
Generating: ctel

And now "./Build install" which is the last step:

[root@centos-32bits App-ClusterSSH-4.03_04]# ./Build install

After installation, let's have a test:

[root@centos-32bits App-ClusterSSH-4.03_04]# echo 'svr testserver1 testserver2' > /etc/clusters

Now run 'cssh svr', and you'll get the charm!



If you met error like below:

Can't connect to display `unix:1': No such file or directory at /usr/local/share/perl5/X11/ line 2264.

And you are connecting to vnc session like below:

root 3291 1 0 07:36 ? 00:00:02 /usr/bin/Xvnc :1 -desktop Yue-test:1 (root) -auth /root/.Xauthority -geometry 1600x900 -rfbwait 30000 -rfbauth /root/.vnc/passwd -rfbport 5901 -fp catalogue:/etc/X11/fontpath.d -pn

Then make sure to do below:

export DISPLAY=localhost:1.0

resolved - switching from Unbreakable Enterprise Kernel Release 2(UEKR2) to UEKR3 on Oracle Linux 6

As we can see from here, the available kernels include the following 3 for Oracle Linux 6:

3.8.13 Unbreakable Enterprise Kernel Release 3 (x86_64 only)
2.6.39 Unbreakable Enterprise Kernel Release 2**
2.6.32 (Red Hat compatible kernel)

On one of our OEL6 VM, we found that it's using UEKR2:

[root@testbox aime]# cat /etc/issue
Oracle Linux Server release 6.4
Kernel \r on an \m

[root@testbox aime]# uname -r

So how can we switch the kernel to UEKR3(3.8)?

If your linux version is 6.4, first do a "yum update -y" to upgrade to 6.5 and uppper, and then reboot the host, and follow steps below.

[root@testbox aime]# ls -l /etc/grub.conf
lrwxrwxrwx. 1 root root 22 Aug 21 18:24 /etc/grub.conf -> ../boot/grub/grub.conf

[root@testbox aime]# yum update -y

If your linux version is 6.5 and upper, you'll find /etc/grub.conf and /boot/grub/grub.conf are different files(for yum update one. If your host is OEL6.5 when installed, then /etc/grub.conf should be softlink too):

[root@testbox ~]# ls -l /etc/grub.conf
-rw------- 1 root root 2356 Oct 20 05:26 /etc/grub.conf

[root@testbox ~]# ls -l /boot/grub/grub.conf
-rw------- 1 root root 1585 Nov 23 21:46 /boot/grub/grub.conf

In /etc/grub.conf, you'll see entry like below:

title Oracle Linux Server Unbreakable Enterprise Kernel (3.8.13-44.1.3.el6uek.x86_64)
root (hd0,0)
kernel /vmlinuz-3.8.13-44.1.3.el6uek.x86_64 ro root=/dev/mapper/vg01-lv_root rd_LVM_LV=vg01/lv_root rd_NO_LUKS rd_LVM_LV=vg01/lv_swap LANG=en_US.UTF-8 KEYTABLE=us console=hvc0 rd_NO_MD SYSFONT=latarcyrheb-sun16 rd_NO_DM rhgb quiet
initrd /initramfs-3.8.13-44.1.3.el6uek.x86_64.img

What you'll need to do is just copying the entries above from /etc/grub.conf to /boot/grub/grub.conf(make sure /boot/grub/grub.conf not be a softlink, else you may met error "Boot loader didn't return any data"), and then reboot the VM.

After rebooting, you'll find the kernel is now at UEKR3(3.8).


If you find the VM is OEL6.5 and /etc/grub.conf is a softlink to /boot/grub/grub.conf, then you could do the following to upgrade kernel to UEKR3:

1. add the following lines to /etc/yum.repos.d/public-yum-ol6.repo:

name=UEKR3 for Oracle Linux 6 ($basearch)

2. List and install UEKR3:

[root@testbox aime]# yum list|grep kernel-uek|grep public_ol6_UEKR3
kernel-uek.x86_64 3.8.13-44.1.5.el6uek public_ol6_UEKR3
kernel-uek-debug.x86_64 3.8.13-44.1.5.el6uek public_ol6_UEKR3
kernel-uek-debug-devel.x86_64 3.8.13-44.1.5.el6uek public_ol6_UEKR3
kernel-uek-devel.x86_64 3.8.13-44.1.5.el6uek public_ol6_UEKR3
kernel-uek-doc.noarch 3.8.13-44.1.5.el6uek public_ol6_UEKR3
kernel-uek-firmware.noarch 3.8.13-44.1.5.el6uek public_ol6_UEKR3
kernel-uek-headers.x86_64 3.8.13-26.2.4.el6uek public_ol6_UEKR3

[root@testbox aime]# yum install -y kernel-uek* --disablerepo=* --enablerepo=public_ol6_UEKR3

3. Reboot

resolved - Exception: ha_check_cpu_compatibility failed:

Today when I tried to add one OVS server in OVMM pool, the following error messages prompted:

2014-11-12 06:25:18.083 WARNING failed:errcode=00000, errmsg=Unexpected error: <Exception: ha_check_cpu_compatibility
failed:<Exception: CPU not compatible! {'new_ovs_03': 'vendor_id=GenuineIntel;cpu_family=6;model=45', 'slce27vmf1002': 'vendor_id=GenuineIntel;cpu_family=6;model=44', 'new_ovs_03': 'vendor_id=GenuineIntel;cpu_family=6;model=45'}>

File "/opt/ovs-agent-2.3/", line 248, in ha_check_cpu_compatibility
raise Exception("CPU not compatible! %s" % repr(d))

File "/opt/ovs-agent-2.3/", line 609, in cluster_check_prerequisite
raise Exception(msg)

File "/opt/ovs-agent-2.3/", line 646, in _cluster_setup
File "/opt/ovs-agent-2.3/", line 340, in _check
raise OVSException(error=ret["error"])

2014-11-12 06:25:18.083 NOTIFICATION Failed setup cluster for agent 2.2.0...
2014-11-12 06:25:18.083 ERROR Cluster Setup when adding server
2014-11-12 06:25:18.087 ERROR [Server Pool Management][Server Pool][test_serverpool]:During adding servers ([new_ovs_03]) to server pool (test_serverpool), Cluster setup failed: (OVM-1011 OVM Manager communication with new_ovs_03 for operation HA Setup for Oracle VM Agent 2.2.0 failed:
errcode=00000, errmsg=Unexpected error: <Exception: ha_check_cpu_compatibility
failed:<Exception: CPU not compatible! {'new_ovs_03': 'vendor_id=GenuineIntel;cpu_family=6;model=45', 'slce27vmf1002': 'vendor_id=GenuineIntel;cpu_family=6;model=44', 'new_ovs_03': 'vendor_id=GenuineIntel;cpu_family=6;model=45'}>


As stated in the error message, the adding failed at cpu check. To resolve this, we can comment out the code where cpu check occurred.

File /opt/ovs-agent-2.3/ in line 646 on each OVS server in the server pool:

#ret = cluster_check_prerequisite(ha_enable=ha_enable)

Then bounce ovs-agent on each OVS server, and try add again. Please note that this WA will make live migration between VMs not possible(actually it's cpu of different arch that makes live migration not possible).

Resolved - AttributeError: 'NoneType' object has no attribute '_imgName'

Today when I tried to list Virtual Machines on one Oracle OVMM, error message prompted:

[root@ovmm_test ~]# ovm -uadmin -ppassword vm ls
Traceback (most recent call last):
  File "/usr/bin/ovm", line 43, in ?
  File "/usr/lib/python2.4/site-packages/ovmcli/", line 122, in main
    return ovm.ovmcli.runcmd(args)
  File "/usr/lib/python2.4/site-packages/ovmcli/", line 147, in runcmd
    return method(options)
  File "/usr/lib/python2.4/site-packages/ovmcli/", line 1578, in do_vm_ls
    result.append((serverpool._serverPoolName, vm._imgName))
AttributeError: 'NoneType' object has no attribute '_imgName'

Then I tried list VMs by server pool:

[root@ovmm_test ~]# ovm -uadmin -ppassword vm ls -s Pool1_test
Name                 Size(MB) Mem   VCPUs Status  Server_Pool
testvm1              17750    8196  4     Running Pool1_test
testvm2               50518    8196  4     Running Pool1_test
testvm3          19546    8192  2     Running Pool1_test
testvm4          50518    20929 4     Running Pool1_test
testvm5          19546    8192  2     Running Pool1_test
[root@ovmm_test ~]# ovm -uadmin -ppassword vm ls -s Pool1_test_A
Traceback (most recent call last):
  File "/usr/bin/ovm", line 43, in ?
  File "/usr/lib/python2.4/site-packages/ovmcli/", line 122, in main
    return ovm.ovmcli.runcmd(args)
  File "/usr/lib/python2.4/site-packages/ovmcli/", line 147, in runcmd
    return method(options)
  File "/usr/lib/python2.4/site-packages/ovmcli/", line 1578, in do_vm_ls
    result.append((serverpool._serverPoolName, vm._imgName))
AttributeError: 'NoneType' object has no attribute '_imgName'

One pool was working and the other was not, so the problematic VMs must reside in pool Pool1_test_A.

Another symptom was that, although ovmcli wouldn't work, the OVMM GUI worked as expected and returns all the VMs.

As ovmcli read entries from Oracle DB(SID XE) on OVMM, so the issue maybe caused by the inconsistency between DB & OVMM agent DB.

I got the list of all VMs on the problematic server pool from OVMM GUI, and then ran the following query to get all entries in DB:

select IMG_NAME from OVS_VM_IMG where SITE_ID=110 and STATUS !='Running' and length(IMG_NAME)>50; #Pool1_test_A was with ID 110, got from table OVS_SITE. I used length() here because in the problematic server pool, VMs all should have IMG_NAME with more than 50 characters; if less than 50, then they were VM templates which should have no issue

Comparing the output from OVMM GUI & OVM DB, I found some entries which only existed in DB. And for all of these entries, they all had "Status" in "Creating", and also the

select IMG_NAME from OVS_VM_IMG where STATUS='Creating';

Then I removed these weird entries:

delete from OVS_VM_IMG where SITE_ID=110 and STATUS !='Running' and length(IMG_NAME)>50; #you can try rename/drop table OVS_VM_IMG(alter table TBL1 rename to TBL2; drop table TBL1), remove entries in backup table(OVS_VM_IMG_bak20141106), and then rename backup table(OVS_VM_IMG_bak20141106) to OVS_VM_IMG if failed at this step caused by foreign key or other reasons (don't do this, it will cause problem about constraints etc)

After this, the issue got resolved.


  1. After you removed entries with STATUS being "Creating", and if you found some more entries of this kind occurred in OVM DB, then maybe it's caused by VM templates not working or DB table corrupted. In this case, you'll need recover OVMM by rollong back to previous version of your backup, and then import VM templates/VM images etc.
  2. Actually the issue was caused by breaking constraint(constraint name conflicts caused by table backups. So better not to backup table when doing operation against OVMM DB using sql directly). This issue can be resolved by alter constraint name, and later remove backup tables.

resolved - IOError: [Errno 2] No such file or directory when creating VMs on Oracle VM Server

Today when I tried to add one OVS server to Oracle VM Server server pool, there was error message like below:

Start - /OVS/running_pool/vm_test
PowerOn Failed : Result - failed:<Exception: return=>failed:<Exception: failed:<IOError: [Errno 2] No such file or directory: '/var/ovs/mount/85255944BDF24F62831E1C6E7101CF7A/running_pool/vm_test/vm.cfg'>

I log on one OVS server and found the path was there. And later I logged on all OVS servers in that server pool and found one OVS server did not have storage repo. So I removed that OVS server from pool and tried to added it back to pool and want to create the VM again. But this time, the following error messages prompted when I tried to add OVS server back:

2014-08-21 02:52:52.962 WARNING failed:errcode=50006, errmsg=Do 'clusterm_init_root_sr' on servers ('testhost1') failed.
File "/opt/ovs-agent-2.3/", line 651, in _cluster_setup
File "/opt/ovs-agent-2.3/", line 340, in _check
raise OVSException(error=ret["error"])

2014-08-21 02:52:52.962 NOTIFICATION Failed setup cluster for agent 2.2.0...
2014-08-21 02:52:52.963 ERROR Cluster Setup when adding server
2014-08-21 02:52:52.970 ERROR [Server Pool Management][Server Pool][test_pool]:During adding servers ([testhost1]) to server pool (test_pool), Cluster setup failed: (OVM-1011 OVM Manager communication with host_master for operation HA Setup for Oracle VM Agent 2.2.0 failed:
errcode=50006, errmsg=Do 'clusterm_init_root_sr' on servers ('testhost1') failed.

From here, I realized that this error was caused by storage repo could not created on that OVS server testhost1. So I logged on testhost1 for a check. As the storage repo was one NFS share, so I tried do a showmount -e <nfs server>, and found it's not working. And then I tried to check the tracert to <nfs server>, and it's not going through.

From another host, showmount -e <nfs server> worked. So the problem was on OVS server testhost1. After more debugging, I found that one NIC was on the host but not pingable. Later I had a check of the switch, and found the NIC was unplugged. I plugged in the NIC and tried again with adding back OVS server, creating VM, and all went smoothly.


Suppose you want to know the NFS clients which mount one share from the NFS server, then on any client that has access to the NFS server, do the following:

[root@centos-doxer ~]# showmount -a|grep to_be

-a or --all

List both the client hostname or IP address and mounted directory in host:dir format. This info should not be considered reliable.


If you met below error when trying to poweron VM:

2016-08-19 02:58:28.474 NOTIFICATION [PowerOn][testvm]: Start - /OVS/running_pool/testvm
2016-08-19 02:58:39.802 NOTIFICATION [PowerOn][testvm]: Result - failed:<error: (113, 'No route to host')>
File "/opt/ovs-agent-2.3/", line 168, in start_vm
raise e
2016-08-19 02:58:39.802 WARNING [PowerOn][testvm]: Result - failed:<error: (113, 'No route to host')>
File "/opt/ovs-agent-2.3/", line 168, in start_vm
raise e

Or below error when trying to import template:

Register an empty virtual machine

register the virtual machine genernal information

get the virtual machine detail information...

Invalid virtual machine type(HVM/PVM).

Then the cause should be the existence of problematic OVS server. You should check ocfs2.conf or remove maintenance OVS server then have a test.

resolved - Kernel panic - not syncing: Attempted to kill init

Today when I tried to poweron one VM hosted on XEN server, the following error messages prompted:

Write protecting the kernel read-only data: 6784k
Kernel panic - not syncing: Attempted to kill init! [failed one]
Pid: 1, comm: init Not tainted 2.6.32-300.29.1.el5uek #1
Call Trace:
[<ffffffff810579a2>] panic+0xa5/0x162
[<ffffffff8109b997>] ? atomic_add_unless+0x2e/0x47
[<ffffffff8109bdf9>] ? __put_css_set+0x29/0x179
[<ffffffff8145744c>] ? _write_lock_irq+0x10/0x20
[<ffffffff81062a65>] ? exit_ptrace+0xa7/0x118
[<ffffffff8105b076>] do_exit+0x7e/0x699
[<ffffffff8105b731>] sys_exit_group+0x0/0x1b
[<ffffffff8105b748>] sys_exit_group+0x17/0x1b
[<ffffffff81011db2>] system_call_fastpath+0x16/0x1b

This is quite weird as it's ok yesterday:

Write protecting the kernel read-only data: 6784k
blkfront: xvda: barriers enabled (tag) [normal one]
xvda: detected capacity change from 0 to 15126289920
xvda: xvda1 xvda2 xvda3
blkfront: xvdb: barriers enabled (tag)
xvdb: detected capacity change from 0 to 16777216000
xvdb: xvdb1
Setting capacity to 32768000
xvdb: detected capacity change from 0 to 16777216000
kjournald starting. Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
SELinux: Disabled at runtime.
type=1404 audit(1406281405.511:2): selinux=0 auid=4294967295 ses=4294967295

After some checking, I found that this OVS server was hosting more than 40 VMs, and the VCPUs was tight. So I turned off some unused VMs and then issue resolved.

Resolved - Your boot partition is on a disk using the GPT partitioning scheme but this machine cannot boot using GPT

Today when I tried to install Oracle VM Server on one server, the following error occurred:

Your boot partition is on a disk using the GPT partitioning scheme but this machine cannot boot using GPT. This can happen if there is not enough space on your hard drive(s) for the installation.

So to went on with the installation, I had to think of a way to erase GPT partition table on the drive.

To do this, the first step is to fall into linux rescue mode when booting from CDROM(another way is when installing OVS, Use Alt-F2 to access a different terminal screen to the installer. Use fdisk from the command line to manually repartition the disk using a dos partition table.):


Later, check with fdisk -l, I could see that /dev/sda was the only disk that needed erasing GPT label. So I used dd if=/dev/zero of=/dev/sda bs=512 count=1 to erase GPT table:




After this, run fdisk -l again, I saw that the partition table was now gone:


Later, re-initializing installation of OVS server. When the following message prompted, select "No":


And select "yes" when below message prompted so that we can make new partition table:


The steps after this was normal ones, and the installation went smoothly.


  • You can disable internal USB device by going to BIOS:

To disable them not participating into system disks when doing system install, you can do below:



  • If the disk is more than 2T, then there's no way to soft convert from GPT to MBR, so you'll need decrease the disk size from BIOS booting process. Here's an example of using LSI Raid Controller MegaRAID BIOS Config Utility Drive 252 to reconfig disks from Oracle iLOM GUI console(you can check here for MegaCLI). (tips - the first sector contains MBR<446 byptes> and partition table<64 byptes>, 3 main partitions and 1 extend partition. The extend partition can have many logical partitions)

Alt + A to enable/disable shortcut select.

When short cut disabled - TAB to move between items, Enter will work as expected when shortcut disabled.

When shortcut enabled - Space key acts as Enter when shortcut enabled.

If you want to go into BIOS, press F2.

Press Ctrl + H to goto MegaRaid WebBIOS(in newer version, press Ctrl + R). Make sure progress is 100% for newly created VD.

屏幕快照 2016-04-11 17.37.27


3-clear configuration

4-add configuration

5-manual configuration










Below is for new version(use small strip size for DB):