Xen tips

Details: Category: Virtualization; Written by Mahdi Bahmani Ciahmard; Hits: 54

xen client config sample:

[root@vmemail ~]# cat /etc/xen/vmlist/win1

# Automtically generated by ConVirt

builder='hvm' maxmem='5000' memory='4091' vcpus=2 name='win1' device_model ='/usr/lib/xen-3.2-1/bin/qemu-dm' kernel='/usr/lib/xen-3.2-1/boot/hvmloader' pae=1 acpi=1 apic=1 localtime=0 vif=['bridge=eth0xenbr94'] #vif=['bridge=xenconsole0'] boot='c' #boot='d' sdl=1 vnc=1 vncunused=1 vncviewer=1 serial='pty' on_poweroff='destroy' on_reboot='restart' on_crash='restart' #disk=['phy:/dev/VGVMlocal1/win1,ioemu:hda,w','file:/home/win2008.iso,hdc,r'] disk=['phy:/dev/VGVMlocal1/win1,ioemu:hda,w', 'phy:/dev/loop1,ioemu:hdc:cdrom,r'] #disk=['phy:/dev/VGVMlocal1/win1,ioemu:hda,w','phy:/dev/hda,hdc,r'] [root@vmemail ~]# this config work on debian for centos run this cmds mkdir -p /usr/lib/xen-3.2-1/boot mkdir -p /usr/lib/xen-3.2-1/bin/ ln -s /usr/lib/xen/boot/hvmloader /usr/lib/xen-3.2-1/boot/hvmloader ln -s /usr/lib64/xen/bin/qemu-dm /usr/lib/xen-3.2-1/bin/qemu-dm ln -s /etc/xen/vmlist /var/cache/convirt/image_store <div style="text-align: left;"><hr /></div> Script that make virtualization interfaces xen:~# cat /etc/init.d/setup_network.sh #!/bin/bash VLANS="10 30 47 49" #Interfaces for virtualization" VIFList="eth0 eth1" #Interfaces for management VIFxenConsole="eth2" #interfaces for connecting xen to storage such az iSCSI storage VIFStorageiSCSI="eth3" function add_if() { ip link set up eth0 ip link set up eth1 ip link set up eth2 ip link set up eth3 echo "Enable IP forwarding" echo 1 > /proc/sys/net/ipv4/ip_forward echo "Set Ethernet parameters for Virtual Interfaces" for i in $VIFList do echo "ethtool -K $i eth0 rx off tx off tso off gso off" ethtool -K $i eth0 rx off tx off tso off gso off done echo echo "Set Ethernet parameters for Virtual Interfaces" echo "ethtool -K $VIFxenConsole sg on rx on tx on tso on gso on" ethtool -K $VIFxenConsole sg on rx on tx on tso on gso on echo "Create Vlans,Bridge and add vlan's to bridges" for i in $VIFList do for z in $VLANS do echo echo "vconfig add $i $z" vconfig add $i $z echo "ifconfig $i.$z up" ifconfig $i.$z up echo "##################" echo echo "brctl addbr $i"xenbr"$z" brctl addbr $i"xenbr"$z echo "brctl addif $i"xenbr"$z $i.$z" brctl addif $i"xenbr"$z $i.$z echo "ifconfig $i"xenbr"$z up" ifconfig $i"xenbr"$z up echo "*********************" done done echo brctl show } function rm_if(){ for i in $VIFList do for z in $VLANS do echo echo echo "brctl delif $i"xenbr"$z $i.$z" brctl delif $i"xenbr"$z $i.$z echo "vconfig rem $i.$z" vconfig rem $i.$z echo "ifconfig $i"xenbr"$z down" ifconfig $i"xenbr"$z down echo "brctl delbr $i"xenbr"$z" brctl delbr $i"xenbr"$z echo "#######################" echo done done brctl show } case "$1" in start) add_if echo "Interfaces's Configurations is done.";; stop) rm_if echo "Virtualization Interfaces is done." ;; esac exit 0 xen:~# <div style="text-align: left;"><hr /></div> <h2 id="error.3ACDROMbootfailure" style="color: #000000; font-family: Arial,'Lucida Grande',sans-serif; font-size: 16px; line-height: normal; text-align: left;">error: CDROM boot failure</h2> You get the error : <ul style="color: #000000; font-family: Arial,'Lucida Grande',sans-serif; font-size: 16px; line-height: normal; text-align: left;"> <li style="list-style-type: none;"> <pre style="border-width: 1pt; border-style: solid; border-color: #aebdcc; background-color: #f3f5f7; padding: 5pt; font-family: courier,monospace; white-space: pre-wrap; word-wrap: break-word;">CDROM boot failure code 0002 or CDROM boot failure code 0003 Boot from cd-Rom failed Fatal: Could not read the boot disk.</pre> </li> </ul> That's because Xen can't boot from a cdrom iso image at the moment. i.e you can't have <tt>tap:aio:/path/to/mycd.iso,hdc:cdrom,r</tt> or <tt>file:/path/to/mycd.iso,hdc:cdrom,r</tt>. Workaround: use losetup to create a loopback device for the cdrom ISO image, then use it in Xen configuration file. for example : <ul style="color: #000000; font-family: Arial,'Lucida Grande',sans-serif; font-size: 16px; line-height: normal; text-align: left;"> <li style="list-style-type: none;"> <pre style="border-width: 1pt; border-style: solid; border-color: #aebdcc; background-color: #f3f5f7; padding: 5pt; font-family: courier,monospace; white-space: pre-wrap; word-wrap: break-word;">#First, check which loop device is free $losetup -f /dev/loop9 #Then create a loopback device $losetup -f /path/to/mycd.iso losetup /dev/loop9 /dev/loop9: [fe04]:3096598 (/path/to/mycd.iso)</pre> </li> </ul> Now you can use /dev/loop9 in xen configuration file (/etc/xen/foobar.cfg) : <ul style="color: #000000; font-family: Arial,'Lucida Grande',sans-serif; font-size: 16px; line-height: normal; text-align: left;"> <li style="list-style-type: none;"> <pre style="border-width: 1pt; border-style: solid; border-color: #aebdcc; background-color: #f3f5f7; padding: 5pt; font-family: courier,monospace; white-space: pre-wrap; word-wrap: break-word;">... disk = [ 'phy:/dev/vg1/xpsp3,ioemu:hda,w', 'phy:/dev/loop/0,ioemu:hdc:cdrom,r' ] ...

then boot/install the guest OS.

note: yo should switch back to the tap:aio:/path/to/mycd.iso,hdc:cdrom,r syntax after installation, since loop back have to be recreated after you reboot the host system.

Serial console access

To get output from grub, XEN, the kernel and getty (login prompt) via both vga and serial console to work, here's an example of the right settings when using Lenny kernels and Xen 3.2:

In /boot/grub/menu.lst:

serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
terminal --timeout=5 serial console
[...]
title           Xen 3.2-1-amd64 / Debian GNU/Linux, kernel 2.6.26-2-xen-amd64
root            (hd0,0)
kernel          /boot/xen-3.2-1-amd64.gz com1=9600,8n1 console=com1,vga
module          /boot/vmlinuz-2.6.26-2-xen-amd64 root=/dev/md0 ro console=tty0 console=hvc0
module          /boot/initrd.img-2.6.26-2-xen-amd64

In contrast to the Etch configuration, there's no ttyS0 in the vmlinuz line!

In /etc/inittab you need at least these lines:

1:2345:respawn:/sbin/getty 38400 hvc0
2:23:respawn:/sbin/getty 38400 tty1
# NO getty on ttyS0!

The tty1 will show up at the vga output, and the hvc0 will show up at the serial console

rc.local

xen:~# cat /etc/rc.local

#!/bin/sh -e

echo 'hwcap 0 nosegneg' > /etc/ld.so.conf.d/libc6-xen.conf && ldconfig

xm mem-set 0 8091

ntpdate -s dc1

iscsiadm -m discovery -t st -p 192.168.200.5

iscsiadm -m node --targetname "iqn.1986-03.com.hp:storage.msa2312i.0938da0e3f" --portal "192.168.200.5:3260" --login

pvscan

vgchange -a y

#iscsiadm -m node --targetname "172.21.0.39:3260,1 iqn.2004-08.jp.buffalo:TS-RIGL333-001D73269333:Vol1" --portal "172.21.0.39:3260" --logout

#dd if=/dev/VGVMlocal/nodelwin2k3r2sp2_001 |ssh This e-mail address is being protected from spambots. You need JavaScript enabled to view it. "dd of=/home/msafizadeh/nodelwin2k3r2sp2_001.iso"

pvscan

vgchange -a y

#For smooth operation and good guest performance you need to make sure dom0 always gets enough CPU time to process and serve the IO requests for guests.

xm sched-credit -d Domain-0 -w 512

#ssh xen02 'lvcreate -L25G -n /dev/VGNetstorage01/DevelopTest'

#for i in `cat /etc/xen/vmlist/currentvm`; do xm create /etc/xen/vmlist/$i; done

#dd if=/dev/VGVMlocal/Deve |pv -s 25G |ssh root@xen02 "dd of=/dev/VGNetstorage01/Deve"

#dd if=/dev/VGVMlocal/nodelwin2k864_ |pv -s 51G |dd of=/dev/VGNetstorage01/Ola bs=8091

#dd if=/dev/VGVMlocal/nodelwin2k3r2sp2_001 |pv -s 52G |ssh root@xen04 "dd of=/dev/VGVMlocal/vmehrdev"

/bin/sh /root/.scripts/Dedicat_CPU_to_xen

mount -t ext3 -o acl,usrquota,grpquota /dev/VGNetstorage01/data /home/data

/etc/init.d/samba restart

/etc/init.d/winbind restart

/etc/init.d/nscd restart

exit 0

xen:~#

How to set the virtual guest clock

By default, the clocks in a Linux VM are synchronized to the clock running on the control domain, and cannot be independently changed (Any attempts to set or modify the time in a guest will fail). This mode is a convenient default, since only the control domain needs to be running the NTP service to keep accurate time across all VMs.

Paravirtualized guests may also perform their own system clock management:

Add the following lines to /etc/sysctl.conf, and reboot the system:
```
# Set independent wall clock time
xen.independent_wallclock = 1
```
You can temporarily override the setting for the current session in the proc filesystem. For example, as root run the following command on the guest:
```
# echo 1 > /proc/sys/xen/independent_wallclock
```
Pass "independent_wallclock=1" as a boot parameter to the VM.

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Serial console access

How to set the virtual guest clock