Xen318: 2017

Tuesday, January 24, 2017

Below is an alternate method that I have used to remove disks owned by control domain

Obtain the UUID of the VM in question

<UUID of VM> = 26708987-c6b2-3243-c49c-db20a96b15a8

From the command line interface run the following command:

xe vbd-list vm-uuid=26708987-c6b2-3243-c49c-db20a96b15a8
uuid ( RO) : 81ae5475-02fd-ba46-68f6-4a170102641a
vm-uuid ( RO): 26708987-c6b2-3243-c49c-db20a96b15a8
vm-name-label ( RO): FvWebProxy01
vdi-uuid ( RO): <not in database>
empty ( RO): true
device ( RO): xvdd

uuid ( RO) : 974dc129-48bf-eac2-ab6c-467ef0dfd620
vm-uuid ( RO): 26708987-c6b2-3243-c49c-db20a96b15a8
vm-name-label ( RO): FvWebProxy01
vdi-uuid ( RO): 8d673a64-26a2-4e8e-8c8d-0cd4efcf2520
empty ( RO): false
device ( RO): xvda

and then execute the following command. NOTE: I chose vdi-uuid 8d673a64 because the other VDI is listed as not in the database

xe vbd-list vdi-uuid=8d673a64-26a2-4e8e-8c8d-0cd4efcf2520
uuid ( RO) : 64cd3f2e-66c4-ae3f-7f53-d83d97d2601f
vm-uuid ( RO): 70ad4283-6d3e-47c6-9c3c-070f586f43c2
vm-name-label ( RO): Control domain on host: FsXENSVR152
vdi-uuid ( RO): 8d673a64-26a2-4e8e-8c8d-0cd4efcf2520
empty ( RO): false
device ( RO): sm/backend/2710d6e3-fb6b-0cdf-0230-845f87620eab/8d673a64-26a2-4e8e-8c8d-0cd4efcf2520

uuid ( RO) : 974dc129-48bf-eac2-ab6c-467ef0dfd620
vm-uuid ( RO): 26708987-c6b2-3243-c49c-db20a96b15a8
vm-name-label ( RO): FvWebProxy01
vdi-uuid ( RO): 8d673a64-26a2-4e8e-8c8d-0cd4efcf2520
empty ( RO): false
device ( RO): xvda

and then run the following command. NOTE: I chose UUID 64cd3f2 because as you can see the vm-name-label is Control domain on host

xe vbd-unplug uuid=64cd3f2e-66c4-ae3f-7f53-d83d97d2601f
The device is not currently attached
device: 64cd3f2e-66c4-ae3f-7f53-d83d97d2601f

xe vbd-destroy uuid=64cd3f2e-66c4-ae3f-7f53-d83d97d2601f

The VM disks that were owned by the control domain should now be gone.

Monday, January 23, 2017

VM disks Owned by the Control Domain

You tried to migrate a VM, move a disk, or take a snapshot, and you look on your SR to find that your VM’s disk is owned by “the control domain”.

1. Why does this happen?

Basically it boils down to disk operations on/from a VM failing. Operations such as move, copy, snapshot, export, etc.

2. How do I get around it?

One answer is to reboot.

Another way is to find the link between your virtual disk and DOM0 (the control domain) from your stand-alone XenServer (or primary server if you have a pool).

Use list_domains to get the UUID of DOM0 (the control domain):

The control domain UUID is 09dffafe-5bec-430d-bc80-6ddb2313beff

Now we have to find the VBD(s) that DOM0 (the control domain) owns:

xe vbd-list vm-uuid=<DOM0 UUID, such as 09dffafe-5bec-430d-bc80-6ddb2313beff id>

This will show information about any Virtual Block Device (VBD) that DOM0 (the control domain) may be hanging onto. What we are interested in is the UUID of the VBD(s).

Grab the VBD’s UUID and execute:

xe vbd-unplug uuid=<UUID of the VBD being held by DOM0>

Finally, run:

xe vbd-destroy uuid=<UUID of the VBD being held by DOM0>

And there – rescan your storage repository and your VDI (virtual disk interface) should be free for your use.

Switch Commands

Dell M8024-k switch

Enable SSH on switch

Connect to switch via CLI

Module A1(config)#crypto key generate dsa

Do you want to overwrite the existing DSA keys? [Y | N] :y

DSA key generation started, this may take a few

minutes..................................................................................................................................

.......................................................
DSA key generation complete.

Module A1(config)#crypto key generate rsa

Do you want to overwrite the existing RSA keys? [Y | N] :y

RSA key generation started, this may take a few minutes....................
RSA key generation complete.

Module A1(config)#ip ssh server

Module A1(config)#exit

Module A1#exit

Module A1>en
Password:***********

Module A1#show ip ssh

SSH Server enabled. Port: 22
Protocol Levels: Versions 1 and 2.
SSH Connections Currently in Use: ............. 0
Maximum number of SSH Sessions Allowed: ....... 5
SSH Session Timeout: .......................... 600
RSA key was generated.
DSA key was generated.
SSH Public Key Authentication is disabled.

Active Incoming Sessions.

Ip Address User Name Idle Time Session Time
--------------- --------------- ------------ ------------

Module A1#exit

Module A1>exit

=====================
Disable Telnet
=====================

config
ip telnet server disable
exit

test a telnet connection to see if it fails

========================================================================

Ran the following command from the command line interface :

config t
line vty 0 4
transport input ssh

line 5 15
transport input ssh

copy run start

I tested a telnet connection and it failed. SSH connection worked successfully.

========================================================================

============
Enable HTTPS
============

Module A2(config)#crypto certificate 1 generate

Module A2(config-crypto-cert)#?

common-name Specifies the common name.
country Specifies the country name.
do Run Privileged Exec mode commands.
duration Specifies number of days a self-signed certi fication
would be valid. If unspecified defaults to 3 65 day.
email Specifies the contact email address.
exit To exit from the mode.
key-generate Regenerate SSL RSA key.
location Specifies the location or city name.
organization-name Specifies the organization name
organization-unit Specifies the organization internal unit
show Show configured settings and operational sta tus.
state Specifies the state or province name.

Module A2(config-crypto-cert)#key-generate ?

<cr> Press enter to execute the command.
<length> Specifies the length of the SSL's RSA key. I f
unspecified, length defaults to 1024.

Module A2(config-crypto-cert)#key-generate

Module A2(config-crypto-cert)#exit

Certification Generation Successful..

Module A2(config)#ip http secure-certificate 1

Module A2(config)#ip http secure-server

Module A2(config)#exit

Module A2#show ip http server secure status

HTTPS Server is Enabled. Port : 443
DH Key exchange enabled.
Certificate 1 is active.
Issued by: self-signed
Valid from Mar 8 05:11:14 2006 GMTMar 8 05:11:14 2007 GMT0.0.0.0 to Mar 8 05:11:14 2007 GMT0.0.0.0
Subject: /CN=0.0.0.0
Fingerprint: DF1027F336CC450ED2AC1C740DF24921

Module A2#show ip telnet

Telnet Server is Disabled. Port : 23

Module A2#show ip http server status

HTTP Server is Disabled. Port : 80