(1) 啓動 Xend 時出現錯誤 ImportError: /usr /lib/python/xen/lowlevel/acm.so: undefined symbol: Py_InitModule4
(2) 使用 virt-install 創建Xen虛擬機時出現錯誤：ERROR virDomainCreateLinux() failed XML描述 domain 不是良好的格式或者無效
(3) virt-manager 中連接虛擬機管理者Dom 0時出現錯誤：虛擬機管理者連接失敗 libvirtError: virConnectOpenReadOnly() failed
(4) virt-install 安裝虛擬機是出現錯誤：ERROR 無法連接到 'localhost:8000': 拒絕連接
(5) virt-manager 安裝Xen虛擬機連接網絡時nat和橋接設備均爲空，無法選擇，安裝不能繼續
(6) virt-manager 或者 virt-install 安裝虛擬機系統過程中出現錯誤：
'libvirt.libvirtError virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working.
(7)半虛擬化安裝，選擇nat上網方式、IP配置使用 DHCP 方式時，虛擬機系統安裝過程卡在 TCP/IP 配置界面，停滯不前
錯誤總結
使用 CentOS 5.2 默認安裝的 Xen，啓動 Xend 時出現如下錯誤：
(1) 啓動 Xend 時出現錯誤 ImportError: /usr /lib/python/xen/lowlevel/acm.so: undefined symbol: Py_InitModule4
--------------------------------------------------------------------------------------
[root@glnode04 ~]# xend
Traceback (most recent call last):
File "/usr/sbin/xend", line 51, in <module>
from xen.xend.server import SrvDaemon
File "/usr/lib64/python/xen/xend/server/SrvDaemon.py", line 20, in <module>
import xen.lowlevel.xc
ImportError: /usr/lib64/python/xen/lowlevel/xc.so: undefined symbol: Py_InitModule4
[root@glnode04 ~]# xm list
Traceback (most recent call last):
File "/usr/sbin/xm", line 8, in <module>
from xen.xm import main
File "/usr/lib/python/xen/xm/main.py", line 45, in <module>
from xen.util import security
File "/usr/lib/python/xen/util/security.py", line 25, in <module>
from xen.lowlevel import acm
ImportError: /usr/lib/python/xen/lowlevel/acm.so: undefined symbol: Py_InitModule4
----------------------------------------------------------------------------------------
############################################
原因分析和解決辦法：
直覺是 python import 時出現的錯誤，查看文件/usr/sbin/xend，第51行是“from xen.xend.server import SrvDaemon”，就是這行出錯。
查看 python 版本
[root@glnode04 ~]# python -V
Python 2.5
查看 python 安裝路徑
[root@glnode04 ~]# which python
/usr/local/bin/python
查看系統安裝的 python 的rpm包版本
[root@glnode04 ~]# rpm -q python
python-2.4.3-21.el5 從這可以看出 python 版本和 rpm 包所示的版本不一致，這個 rpm 包是 CentOS 5.2 自帶的.
系統是CentOS 5.2, 我們發現使用的不是CentOS 5.2 默認安裝的 python，默認安裝的是 Python 2.4.3，CentOS 5.2 默認將python安裝在/usr/bin下。
[root@glnode04 ~]# /usr/bin/python -V
Python 2.4.3
由此可以想到可能是環境變量 PATH 的設置導致我們在命令行執行 python 時使用的是 /usr/local/bin/python，可能是 PATH 的值中 /usr/local/bin 在 /usr/bin 之前；
檢查 ~/.bashrc 發現的確如此，環境變量 PATH 設置是 export PATH=/usr/local/bin:$PATH，將其修改爲
export PATH=$PATH:/usr/local/bin，然後 source ~/.bashrc，或者退出 shell，重新開啓一個 shell，
測試 python ，發現使用的是默認版本。
[root@glnode04 ~]# python -V
Python 2.4.3
啓動 Xend ，正常，沒有問題。
[root@glnode04 ~]# xm list
Error: Unable to connect to xend: No such file or directory. Is xend running?
[root@glnode04 ~]# xend
usage: /usr/sbin/xend {start|stop|restart}
[root@glnode04 ~]# xend start
[root@glnode04 ~]# xm list
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 7931 8 r----- 463.9
分析原因，是因爲 Xen 是python寫的，執行 Xen 相關工具時需要調用 python 相關庫，如果版本對應不一致，或者庫路徑不一致，則會出錯。
############################################
(2) 使用 virt-install 創建Xen虛擬機時出現錯誤： ERROR virDomainCreateLinux() failed XML描述 domain 不是良好的格式或者無效
----------------------------------------------------------------------------------------
[root@glnode04 vm02-CentOS-5.5]# virt-install -n vm01-CentOS-5.5 -r 1024 --vcpus=4 -f vm01-CentOS-5.5.img -s 20 --nographic -l http://10.10.113.14:8888/mirrors/CentOS/5.5/
Would you like a fully virtualized guest (yes or no)? This will allow you to run unmodified operating systems.no
Starting install...
Retrieving file .treeinfo 100% |=========================| 417 B 00:00
Retrieving file vmlinuz.. 100% |=========================| 2.0 MB 00:00
Retrieving file initrd.im 100% |=========================| 7.7 MB 00:00
virDomainCreateLinux() failed XML描述 domain 不是良好的格式或者無效
Domain installation may not have been
successful. If it was, you can restart your domain
by running 'virsh start vm02-CentOS-5.5'; otherwise, please
restart your installation.
三, 20 4月 2011 19:21:08 ERROR virDomainCreateLinux() failed XML描述 domain 不是良好的格式或者無效
Traceback (most recent call last):
File "/usr/bin/virt-install", line 502, in ?
main()
File "/usr/bin/virt-install", line 462, in main
dom = guest.start_install(conscb,progresscb)
File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 813, in start_install
return self._do_install(consolecb, meter)
File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 834, in _do_install
self.domain = self.conn.createLinux(install_xml, 0)
File "/usr/lib64/python2.4/site-packages/libvirt.py", line 573, in createLinux
if ret is None:raise libvirtError('virDomainCreateLinux() failed', conn=self)
libvirtError: virDomainCreateLinux() failed XML描述 domain 不是良好的格式或者無效
----------------------------------------------------------------------------------------
############################################
解決辦法：
安裝前先啓動 libvirtd 服務。
[root@glnode04 vm02-CentOS-5.5]# /etc/init.d/libvirtd status
libvirtd is stopped
[root@glnode04 vm02-CentOS-5.5]# /etc/init.d/libvirtd start
Starting libvirtd daemon: [ OK ]
原因分析:
出現此報錯應該是主機的libvirtd服務沒有啓動，而virt-install工具在進行客戶機系統安裝的時候錯誤地將客戶機的網卡連接到libvirtd服務起的網橋virbr0上，此時libvirtd是關閉的，所以virbr0也不存在了，就出現了上面的錯誤信息。
解決方法有兩個：
（i）啓動libvirtd服務後重新用原來的virt-install命令安裝客戶機操作系統；
#/etc/init.d/libvirtd start
（ii）、在原來的virt-install命令後面加-b參數指定需要連接的網橋，如果未調整網絡，一般默認的網橋應該爲xenbr0
要查看網橋的名稱可以使用brctl命令查看
[root@glnode04 vm02-CentOS-5.5]# /etc/init.d/libvirtd status
libvirtd is stopped
[root@glnode04 vm02-CentOS-5.5]# brctl show # libvirtd是關閉時網橋virbr0也不存在
bridge name bridge id STP enabled interfaces
[root@glnode04 vm02-CentOS-5.5]# /etc/init.d/libvirtd start
Starting libvirtd daemon: [ OK ]
[root@glnode04 vm02-CentOS-5.5]# /etc/init.d/libvirtd status
libvirtd (pid 20863) is running...
[root@glnode04 vm02-CentOS-5.5]# brctl show
bridge name bridge id STP enabled interfaces
virbr0 8000.000000000000 yes
此處我們已經關閉了libvirtd服務，剩下的網橋的名稱爲xenbr0（如果創建了多個網橋，選擇自己需要的網橋名稱）
#virt-install -n kiro-test -r 256 --vcpus=1 -f /data/rh5 --nographics -p -d -l "http://192.168.0.1" -b xenbr0
參考： XEN故障與解決方法彙總
############################################
(3) virt-manager 中連接虛擬機管理者Dom 0時出現錯誤：虛擬機管理者連接失敗 libvirtError: virConnectOpenReadOnly() failed
----------------------------------------------------------------------------------------
Unable to open connection to hypervisor URI 'xen:///':
libvirt.libvirtError virConnectOpenReadOnly() failed
Traceback (most recent call last):
File "/usr/share/virt-manager/virtManager/connection.py", line 307, in _open_thread
self.vmm = libvirt.openReadOnly(self.uri)
File "/usr/lib64/python2.4/site-packages/libvirt.py", line 132, in openReadOnly
if ret is None:raise libvirtError('virConnectOpenReadOnly() failed')
libvirtError: virConnectOpenReadOnly() failed
----------------------------------------------------------------------------------------
############################################
解決：
修改 xen 配置文件，按如下方式修改：
[root@glnode04 ~]# vim /etc/xen/xend-config.sxp
(xend-http-server yes)
(xend-unix-server yes)
重新啓動 Xend 服務
[root@glnode04 ~]# xend restart
############################################
(4) virt-install 安裝虛擬機是出現錯誤：ERROR 無法連接到 'localhost:8000': 拒絕連接
----------------------------------------------------------------------------------------
[root@gmnode14 vm01-CentOS-5.5]# virt-install -n vm01-CentOS-5.5 -r 1024 --vcpus=4 -f vm01-CentOS-5.5.img -s 20 --nographic -l nfs:10.10.113.14:/opt/CentOS/mirrors/5.5
ERROR 無法連接到 'localhost:8000': 拒絕連接
Traceback (most recent call last):
File "/usr/sbin/virt-install", line 861, in ?
main()
File "/usr/sbin/virt-install", line 636, in main
conn = cli.getConnection(options.connect)
File "/usr/lib/python2.4/site-packages/virtinst/cli.py", line 126, in getConnection
conn = libvirt.open(connect)
File "/usr/lib64/python2.4/site-packages/libvirt.py", line 159, in open
if ret is None:raise libvirtError('virConnectOpen() failed')
libvirtError: 無法連接到 'localhost:8000': 拒絕連接
----------------------------------------------------------------------------------------
############################################
解決：
修改 Xend 配置文件，然後，xend restart
[root@gmnode14 yum.repos.d]# vim /etc/xen/xend-config.sxp
(xend-http-server yes)
(xend-unix-server yes)
(xend-port 8000)
############################################
(5) virt-manager 安裝Xen虛擬機連接網絡時nat和橋接設備均爲空，無法選擇，安裝不能繼續
############################################
分析原因：
出現此報錯應該是主機的libvirtd服務沒有啓動，
而virt-install工具在進行客戶機系統安裝的時候錯誤地將客戶機的網卡連接到libvirtd服務起的網橋virbr0上，此時libvirtd是關閉的，所以virbr0也不存在了，就出現了上面的錯誤信息。
解決方法：
啓動libvirtd服務後重新運行 virt-manager 來安裝客戶機操作系統；
#/etc/init.d/libvirtd start
但是這也只能保證 nat 選項中有 default 選項，橋接仍不能選擇設備，要徹底解決Xen虛擬機網絡設備問題請參考問題(6)
參考： XEN故障與解決方法彙總
############################################
(6) virt-manager 或者 virt-install 安裝虛擬機系統過程中出現錯誤：
'libvirt.libvirtError virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working.
---------------------------------------------------------------------------------------
Unable to complete install 'libvirt.libvirtError virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working. ')
Traceback (most recent call last):
File "/usr/share/virt-manager/virtManager/create.py", line 611, in do_install
dom = guest.start_install(False, meter = meter)
File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 813, in start_install
return self._do_install(consolecb, meter)
File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 834, in _do_install
self.domain = self.conn.createLinux(install_xml, 0)
File "/usr/lib64/python2.4/site-packages/libvirt.py", line 573, in createLinux
if ret is None:raise libvirtError('virDomainCreateLinux() failed', conn=self)
libvirtError: virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working.')
'---------------------------------------------------------------------------------------
############################################
原因分析：
從錯誤提示中可以查看到設備(vif) 不能連接，突然想到之前創建虛擬機時在網絡連接設置時橋接方式不能選擇，只能選擇nat方式連接網絡(見問題5)，很可能和這個問題也有關係；
解決辦法：
因爲我使用的機器是好幾年前的，系統是 Cent OS 5.2，不知道xen相關包有沒有安裝正常，於是使用 yum -y install xen* 重新安裝了 xen 相關包，發現有幾個包的確沒有安裝上 。安裝完畢，重啓系統後創建虛擬機，該問題不再出現。
如何使用 yum 安裝xen相關軟件包，請參見 CentOS 5.4下使用yum安裝Xen
2011-04-29 更新該問題
後來我在另外一臺機器上做實驗室時一直提示該錯誤，就算重新安裝了 xen，還是無法解決問題，後來終於從一個國外的網站上得到了提示，這個網站現在不記得了，忘記蒐藏了。
網站上說，啓動虛擬機橋接設備需要這樣幾個內核模塊支持：netbk ，netloop，於是我使用 modprobe 命令手動加載了這兩個模塊，並且重新啓動了 xend，這是生成了網橋設備 xenbr0，
我的測試和使用日誌如下：
安裝虛擬機系統時，出現以下錯誤：
virt-install -n vm02-CentOS-5.5-full -r 2048 --vcpus=4 -f vm02-CentOS-5.5-full.img -s 20 --nographic -l http://10.10.103.14:8088/CentOS/5.5/
[root@hdfs05 vm01-CentOS-5.5-full]# ./install_vm.sh
Would you like a fully virtualized guest (yes or no)? This will allow you to run unmodified operating systems. yes
Starting install...
Retrieving file .treeinfo 100% |=========================| 417 B 00:00
Retrieving file boot.iso. 100% |=========================| 10 MB 00:00
Creating storage file... 100% |=========================| 20 GB 00:00
virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working.')
Domain installation may not have been
successful. If it was, you can restart your domain
by running 'virsh start vm02-CentOS-5.5-full'; otherwise, please
restart your installation.
二, 26 4月 2011 09:23:28 ERROR virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working.')
Traceback (most recent call last):
File "/usr/bin/virt-install", line 502, in ?
main()
File "/usr/bin/virt-install", line 462, in main
dom = guest.start_install(conscb,progresscb)
File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 813, in start_install
return self._do_install(consolecb, meter)
File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 834, in _do_install
self.domain = self.conn.createLinux(install_xml, 0)
File "/usr/lib64/python2.4/site-packages/libvirt.py", line 573, in createLinux
if ret is None:raise libvirtError('virDomainCreateLinux() failed', conn=self)
libvirtError: virDomainCreateLinux() failed POST操作失敗: (xend.err 'Device 0 (vif) could not be connected. Hotplug scripts not working.')
這是 xenbr0、vif0.0 未啓動導致的問題。
重啓機器後
[root@hdfs05 ~]# xend start
[root@hdfs05 ~]# xm list
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 7931 8 r----- 40.5
[root@hdfs05 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1A
inet addr:10.10.111.5 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4942 errors:0 dropped:0 overruns:0 frame:0
TX packets:111 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:681358 (665.3 KiB) TX bytes:14358 (14.0 KiB)
Memory:d8320000-d8340000
eth1 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1B
inet addr:10.10.141.4 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:20 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4970 (4.8 KiB) TX bytes:552 (552.0 b)
Memory:d8360000-d8380000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:87189 errors:0 dropped:0 overruns:0 frame:0
TX packets:87189 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:118287320 (112.8 MiB) TX bytes:118287320 (112.8 MiB)
[root@hdfs05 ~]# /etc/init.d/libvirtd
Usage: /etc/init.d/libvirtd {start|stop|status|restart|condrestart|reload}
[root@hdfs05 ~]# /etc/init.d/libvirtd status
libvirtd is stopped
[root@hdfs05 ~]# /etc/init.d/libvirtd start 啓動 libvirtd 服務
Starting libvirtd daemon: [ OK ]
[root@hdfs05 ~]# ifconfig ，生成了網橋設備 virbr0
eth0 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1A
inet addr:10.10.111.5 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5082 errors:0 dropped:0 overruns:0 frame:0
TX packets:175 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:710500 (693.8 KiB) TX bytes:23050 (22.5 KiB)
Memory:d8320000-d8340000
eth1 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1B
inet addr:10.10.141.4 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:20 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4970 (4.8 KiB) TX bytes:552 (552.0 b)
Memory:d8360000-d8380000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:87613 errors:0 dropped:0 overruns:0 frame:0
TX packets:87613 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:118861744 (113.3 MiB) TX bytes:118861744 (113.3 MiB)
virbr0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:328 (328.0 b)
[root@hdfs05 ~]# xend stop
[root@hdfs05 ~]# /etc/init.d/libvirtd stop
Stopping libvirtd daemon: [ OK ]
[root@hdfs05 ~]# /etc/init.d/libvirtd start
[root@hdfs05 ~]# xend start
[root@hdfs05 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1A
inet addr:10.10.111.5 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5508 errors:0 dropped:0 overruns:0 frame:0
TX packets:299 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:757440 (739.6 KiB) TX bytes:42402 (41.4 KiB)
Memory:d8320000-d8340000
eth1 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1B
inet addr:10.10.141.4 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:20 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4970 (4.8 KiB) TX bytes:552 (552.0 b)
Memory:d8360000-d8380000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:91038 errors:0 dropped:0 overruns:0 frame:0
TX packets:91038 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:123483512 (117.7 MiB) TX bytes:123483512 (117.7 MiB)
virbr0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:398 (398.0 b)
xenbr0 未啓動，
查看Xend啓動日誌，出現錯誤“Link veth0 is missing”
[root@hdfs05 ~]# vim /var/log/xen/xend-debug.log
1
2 Link veth0 is missing.
3 This may be because you have reached the limit of the number of interfaces
4 that the loopback driver supports. If the loopback driver is a module, you
5 may raise this limit by passing it as a parameter (nloopbacks=<N>); if the
6 driver is compiled statically into the kernel, then you may set the parameter
7 using loopback.nloopbacks=<N> on the domain 0 kernel command line.
8
使用腳本手動啓動，出現錯誤
[root@hdfs05 ~]# /etc/xen/scripts/network-bridge status
============================================================
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:1d:7d:48:38:1a brd ff:ff:ff:ff:ff:ff
inet 10.10.111.5/16 brd 10.10.255.255 scope global eth0
inet6 fe80::21d:7dff:fe48:381a/64 scope link
valid_lft forever preferred_lft forever
Device "xenbr0" does not exist.
[root@hdfs05 ~]# /etc/xen/scripts/network-bridge start
Link veth0 is missing.
This may be because you have reached the limit of the number of interfaces
that the loopback driver supports. If the loopback driver is a module, you
may raise this limit by passing it as a parameter (nloopbacks=<N>); if the
driver is compiled statically into the kernel, then you may set the parameter
using loopback.nloopbacks=<N> on the domain 0 kernel command line.
查看加載的模塊
[root@hdfs05 ~]# lsmod | grep net
nfnetlink 40457 2 ip_nat,ip_conntrack
正常情況下的 glnode04 上是：
[root@glnode04 Xenoprof]# lsmod | grep net
netloop 40129 0
netbk 129153 0 [permanent]
手動加載模塊 netbk ，netloop
[root@hdfs05 ~]# modprobe netloop
[root@hdfs05 ~]# modprobe netbk
[root@hdfs05 ~]# lsmod | grep net
netbk 129153 0 [permanent]
netloop 40129 0
nfnetlink 40457 2 ip_nat,ip_conntrack
模塊加載後重啓 xend,
[root@hdfs05 ~]# xend stop
[root@hdfs05 ~]# xend start 啓動消耗很長時間，像死機一樣，網絡跟斷了一樣，bash關閉了，過一段時間後網絡好了。
......
[root@hdfs05 ~]# ps -ef | grep xend
root 4504 1 0 09:35 ? 00:00:00 python /usr/sbin/xend start
root 4505 4504 0 09:35 ? 00:00:00 python /usr/sbin/xend start
root 4813 4773 0 09:37 pts/1 00:00:00 grep xend
開啓另外一個 bash，查看設備，發現 xenbr0 設備啓動了
[root@hdfs05 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1A
inet addr:10.10.111.5 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381a/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1079 errors:0 dropped:0 overruns:0 frame:0
TX packets:80 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:158475 (154.7 KiB) TX bytes:12704 (12.4 KiB)
eth1 Link encap:Ethernet HWaddr 00:1D:7D:48:38:1B
inet addr:10.10.141.4 Bcast:10.10.255.255 Mask:255.255.0.0
inet6 addr: fe80::21d:7dff:fe48:381b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:552 (552.0 b)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:107602 errors:0 dropped:0 overruns:0 frame:0
TX packets:107602 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:145810320 (139.0 MiB) TX bytes:145810320 (139.0 MiB)
peth0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:7926 errors:0 dropped:0 overruns:0 frame:0
TX packets:803 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1048526 (1023.9 KiB) TX bytes:140794 (137.4 KiB)
Memory:d8320000-d8340000
peth1 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:32 errors:0 dropped:0 overruns:0 frame:0
TX packets:278 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:6444 (6.2 KiB) TX bytes:35772 (34.9 KiB)
Memory:d8360000-d8380000
vif0.0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:101 errors:0 dropped:0 overruns:0 frame:0
TX packets:1098 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:17258 (16.8 KiB) TX bytes:159729 (155.9 KiB)
vif0.1 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:552 (552.0 b) TX bytes:0 (0.0 b)
virbr0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:192.168.122.1 Bcast:192.168.122.255 Mask:255.255.255.0
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:468 (468.0 b)
xenbr0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:629 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:107389 (104.8 KiB) TX bytes:0 (0.0 b)
xenbr1 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:440 (440.0 b) TX bytes:0 (0.0 b)
[root@hdfs05 ~]# xend stop
[root@hdfs05 ~]# xend start 生成的網橋設備不變，xend啓動一次後，設備即生成了
[root@hdfs05 ~]# xm list
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 7931 8 r----- 52.0
查看網橋設備
[root@hdfs05 ~]# brctl show
bridge name bridge id STP enabled interfaces
virbr0 8000.000000000000 yes
xenbr0 8000.feffffffffff no peth0
vif0.0
xenbr1 8000.feffffffffff no peth1
vif0.1
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(7)半虛擬化安裝，選擇nat上網方式、IP配置使用 DHCP 方式時，虛擬機系統安裝過程卡在 TCP/IP 配置界面，停滯不前
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半虛擬化安裝時，選擇 nat 上網方式，IP 配置使用 DHCP 方式，此時卡在 TCP/IP 配置界面，
Xen Sending request for IP information for eth0 不能成功, 卡在這裏，不能通過。
--------------------------------------------------------------------------------------------------------
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解決辦法：
IP選擇手動配置，配置 ip地址/子網掩碼；
全虛擬化安裝時不存在此問題。
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(8) 啓動虛擬機時出現錯誤：File "/usr/bin/pygrub", line 28, in ? ImportError: No module named LiloConf
--------------------------------------------------------------------------------------------------------
[root@glnode04 xen]# xm create /etc/xen/vm01-centos-5.5-pv
Using config file "/etc/xen/vm01-centos-5.5-pv".
Traceback (most recent call last):
File "/usr/bin/pygrub", line 28, in ?
import grub.LiloConf
ImportError: No module named LiloConf
提示 /usr/bin/pygrub 文件的第 28 行的 import grub.LiloConf 出錯，這又是 python 的問題，import 出錯。
手動執行 pygrub 命令，仍是出現這樣的錯誤.
[root@glnode04 xen]# /usr/bin/pygrub
Traceback (most recent call last):
File "/usr/bin/pygrub", line 28, in ?
import grub.LiloConf
ImportError: No module named LiloConf
正常情況下執行 /usr/bin/pygrub 是這樣的
[root@gmnode14 xen]# /usr/bin/pygrub
Usage: /usr/bin/pygrub [-q|--quiet] [-i|--interactive] [--output=] [--kernel=] [--ramdisk=] [--args=] [--entry=] <p_w_picpath>
[root@gmnode14 xen]#
--------------------------------------------------------------------------------------------------------
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查看 /usr/lib 下 python 庫，發現有3項:
[root@glnode04 xen]# ls /usr/lib/python
python/ python2.3 python2.4/
這地方有問題，CentOS默認安裝的是Python 2.4.3，庫文件和可執行文件的路徑是:
/usr/lib/python2.4
/usr/bin/python2.4
而現在多了兩個庫文件python和python2.3，將這兩項刪除，或者重命名，再次測試，問題解決。
[root@glnode04 xen]# /usr/bin/pygrub
Usage: /usr/bin/pygrub [-q|--quiet] [-i|--interactive] [--output=] [--kernel=] [--ramdisk=] [--args=] [--entry=] <p_w_picpath>
[root@glnode04 xen]# xm create /etc/xen/vm02-CentOS-5.5-pv
Using config file "/etc/xen/vm02-CentOS-5.5-pv".
Started domain vm02-CentOS-5.5-pv
啓動虛擬機正常.
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