List of VMs on XenServer (with UUIDs)

Xen XE command is a very powerful tool, especially if you bind it with other UNIX tools such as awk. Let say we need a map of vm uuids and theirs names. We can use an output from the vm-list command and parse if with awk to get desire result.

xe vm-list | \
awk '{if ( $0 ~ /uuid/) {uuid=$5} if ($0 ~ /name-label/) \
{$1=$2=$3="";vmname=$0; printf "%s - %s\n", vmname, uuid}}'

The script first save the fifth column from a line having uuid string in it into the variable uuid. Next it saves all columns, after the third one, from line having name-label into variable vmname. Finally it prints both variables.

The exemplary output:

ukweb2 - fbca0851-35de-2963-bf0c-7980f3c0d96f
nagios - b741def2-14cc-def4-f8ba-ff0d3ed741d9
ukmail1 - 343c8f93-e4db-d0df-bc30-7544fcd6f14e
jira - ecc3241f-ac14-0398-4e44-ba96cd1d51d2
dodb-02 - 7f223172-e43e-a200-6dc6-b108ce4f9166
RTST-Witness Server - 3c236b0a-209f-6ac9-6d46-b14f7678bfa6
hub-01 - 60ef767c-9b87-edf8-9f13-af2185e656cd
ukweb1 - 6e0e4622-ddfe-0db8-a128-f432e05565cb
dns2 - d65e40d4-ea21-1cbf-cc86-9f522f5e04ef
ixchariot - 73f78129-86db-fd9f-81b4-85768eeee487

We can modify our command to prepare a list of all host with vms bind to them. This time we use xe vm-list with params=all option. The scripts searches for lines with the name-label and saves a name (third column). Next it looks for lines with the word affinity and a uuid (we know that UUID have to start from a hexadecimal number) and prints a saved name.

xe vm-list params=all| \
awk '{if ( $0 ~ /name-label/) {$1=$2=$3=""; vmname=$0} \
if ($0 ~ /affinity.*\:\ [a-e,0-9]/) {host=$4; printf "%s \n", vmname}}'

The output might looks similar to:

Control domain on host: p1-m4 
   Control domain on host: p1-m2 
   dodb-02 
   ukweb5
   Control domain on host: p1-m3 
   Control domain on host: p1-m1 

You might wonder why the list is so short, but we have the list of machine enforce to start from a given host (affinity to a given UUID). If you have machine on share storage allowed to flow between machine you should get very short list indeed.

XenDebian.py to install Debian on XenServer/XCP

Recently, I've needed to install many Debian VMs onto XenServers and, of course, wanted to automate it. One of my colleagues pointed that rather use existing tools like Cobbler I should take opportunity of working with world leading XenAPI developers and learnt it by writing some code. I took that advice and started to write a python script.

During that I decided that I could improve XenAPI documentation. I spent some extra time on my program and tried to write the code clear and with as many comments as possible, so other can learn from it and reuse it. I hoped to write even more documentation (some tutorial) based on my experiences, unfortunately I haven't had enough time.

Please find short XenDebian.py documentation on Xen wiki:

http://wiki.xen.org/wiki/XenDebian.py

and code on GitHub:

https://github.com/wawrzek/XenDebian


The script is called XenDebian, but with minor modification (new preseed file and change distro name in few places) you should be able to use it with Ubuntu. With a few more modification it should works for any distribution.

Finally, thanks to Project Kronos you would be soon able to install use XenDebian to install many Debian on Debian!

xe-patch

Recently I wrote a very small script to apply XenServer patches from command line.

#!/bin/bash

unzip $1
filename=`basename $1 .zip`.xsupdate
echo "Applying $filename"
xe patch-pool-apply uuid=`xe patch-upload file-name=$filename`

To use if first you need to download a patch (you might try to find any new patch here), and next use the script:

./xe-patch hotfix.zip

Mount LVM from domU in dom0

Mounting logical volumes (LVM) from domX (guest) within dom0 (XenServer) is very not recommender and suggested. But sometimes it might be the only options, and it's cool hacker (hacker in good old meaning, not cracker) trick. So to mount your volume you should take following steps:

1. xe vm-disk-list vm=test4 - list disk of the VM.
2. xe vm-list - find info (UUID) about dom0.
3. xe vbd-create device=xvda unpluggable=true vdi-uuid=79a7a556-a6ba-48cf-8c82-30fa5bb9597c vm-uuid=36895434-e6d7-4fea-8271-d5477ca23c6d - create unpluggable VBD (xvda) with disk (uuid from point 1) on dom0 (uuid from point 2).
4. xe vbd-plug uuid=0a4151b6-2b59-2fdb-c0a9-492520a8d52c - plug created vbd.
5. mount /dev/xvda1 /mnt - mount disk (any 'physical partition').
6. vi /etc/lvm/lvm.conf - if you need anything on LVM you have to edit lvm.conf 

# Ignore /dev/xvd* devices to prevent deadlocking when live-snapshotting
# dom0-attached LVHD VDIs
#filter = "r|/dev/xvd.|","r|/dev/VG_Xen.*/LV.*|"

7. vgchange -a y test4 - activate new vg.
8. mount /dev/test4/root /test/mnt - mount partition.

XenServer, xe and more greping

In my last post I described how you can use grep to extend listing of XenServer parameters. Continuing this thread today, I show how to get values of specific parametes, let say memory.

You can get memory using following command, but I bet it's not you expect.

# xe vm-list params=memory
memory (MRO)    : 


memory (MRO)    : 

More interesting values you can get using params=all. The problem is that you will get hundreds of other values too. This is not helpful, but of course  grep can help us:

# xe vm-list params=all| grep memory
                 memory-actual ( RO): 536870912
                 memory-target ( RO): 
               memory-overhead ( RO): 6291456
             memory-static-max ( RW): 536870912
            memory-dynamic-max ( RW): 536870912
            memory-dynamic-min ( RW): 536870912
             memory-static-min ( RW): 536870912
               recommendations ( RO): 
                        memory (MRO): 
                 memory-actual ( RO): 500170752
                 memory-target ( RO): 
               memory-overhead ( RO): 15728640
             memory-static-max ( RW): 789839872
            memory-dynamic-max ( RW): 500170752
            memory-dynamic-min ( RW): 500170752
             memory-static-min ( RW): 395313152
                        memory (MRO): 
                 memory-actual ( RO): 1073741824
                 memory-target ( RO): 
               memory-overhead ( RO): 10485760
             memory-static-max ( RW): 1073741824
            memory-dynamic-max ( RW): 1073741824
            memory-dynamic-min ( RW): 1073741824
             memory-static-min ( RW): 1073741824
               recommendations ( RO): 
                        memory (MRO): 

It's not so useful yet, because we have only memory related value, but we don't know relation between them and VMs. Luckily, we can very easily extend our grep.

# xe vm-list params=all| grep "label\|memory"
                    name-label ( RW): at10
                 memory-actual ( RO): 536870912
                 memory-target ( RO): 
               memory-overhead ( RO): 6291456
             memory-static-max ( RW): 536870912
            memory-dynamic-max ( RW): 536870912
            memory-dynamic-min ( RW): 536870912
             memory-static-min ( RW): 536870912
               recommendations ( RO): 
                        memory (MRO): 
                    name-label ( RW): Control domain on host: dt33
                 memory-actual ( RO): 500170752
                 memory-target ( RO): 
               memory-overhead ( RO): 15728640
             memory-static-max ( RW): 789839872
            memory-dynamic-max ( RW): 500170752
            memory-dynamic-min ( RW): 500170752
             memory-static-min ( RW): 395313152
                        memory (MRO): 
                    name-label ( RW): at11
                 memory-actual ( RO): 1073741824
                 memory-target ( RO): 
               memory-overhead ( RO): 10485760
             memory-static-max ( RW): 1073741824
            memory-dynamic-max ( RW): 1073741824
            memory-dynamic-min ( RW): 1073741824
             memory-static-min ( RW): 1073741824
               recommendations ( RO): 
                        memory (MRO): 

Now we know that the at10 has 0.5GB, the at11 1GB and the dom0 might have between 386 and 771 MB.

Summary

Of course similar construction in grep query might be use for other variables.E.g. to have the list of live VMs try:

xe vm-list params=all| grep -i -E '(label|\s+live)'

XenServer CLI and grep by name

One of the annoying thing in XenServer command line tool (xe) is lack of regexp/wildcards in filtering vm (and other objects) by name. However, there is easy way to work around thanks to grep. Standard output have 3 lines per vm, with one line before (-B 1 in grep) and one after (-A 1) line with name. So you can use following line to find information about VM with given name:

xe vm-list | grep -B 1 -A 1 your-vm-name

You can also extend this command to get uuid of requested vm:

xe vm-list | grep -B 1  your-vm-name| awk '/uuid/ {print $5}'

What can be use i.e. to take the snapshot:

vm-uuid=`xe vm-list | grep -B 1  dowa| awk '/uuid/ {print $5}'`
xe vm-clone name-name-label='dowa-01-clone' uuid=$vm-uuid

Xenserver & ipmitool

I found that to enable access BMC information locally from Xenserver you need to load following modules:

•  modprobe ipmi_msghandler
•  modprobe ipmi_devintf
•  modprobe ipmi_si

 and latter as normal:
  ipmitool -I open channel info


Tested on Dell R310 without Drac module.



Another thing worth to note  about Dell and it's BMC — it is not enable by default and you need to press Ctrl+E in the right moment and turn it on. 

UPDATE

Dell support was wrong I can turn on access to BMC over LAN without rebooting box:

• ipmitool -I open lan set 1 access on
• ipmitool -I open lan set 1 user
• ipmitool -I open lan set 1 ipsrc dhcp

I'm not sure if I needed all three command. I'll check another day.

IPMITOOL man:  http://ipmitool.sourceforge.net/manpage.html

Upgrade Dell BIOS from XenServer 5.6

I've just found that to upgrade the Dell BIOS for R310 (and I guess other servers) on XenServer 5.6 you have to provide the lockfile file which comes from the procmail RPM.