virt-v2v-input-xen - Using virt-v2v to convert guests from Xen
virt-v2v -ic 'xen+ssh://[email protected]'
-ip passwordfile
GUEST_NAME [-o* options]
This page documents how to use
virt-v2v(1) to convert guests from RHEL 5
Xen, or SLES and OpenSUSE Xen hosts.
You can use SSH password authentication, by supplying the name of a file
containing the password to the
-ip option (note this option does
not take the password directly). You may need to adjust
/etc/ssh/sshd_config on the Xen server to set
"PasswordAuthentication yes".
If you are not using password authentication, an alternative is to use
ssh-agent, and add your ssh public key to
/root/.ssh/authorized_keys
(on the Xen host). After doing this, you should check that passwordless access
works from the virt-v2v server to the Xen host. For example:
$ ssh [email protected]
[ logs straight into the shell, no password is requested ]
Note that support for non-interactive authentication via the
-ip option
is incomplete. Some operations remain that still require the user to enter the
password manually. Therefore ssh-agent is recommended over the
-ip
option. See
https://bugzilla.redhat.com/1854275.
With some modern ssh implementations, legacy crypto algorithms required to
interoperate with RHEL 5 sshd are disabled. To enable them, you may need to
add the following "Host" stanza to your
~/.ssh/config:
Host xen.example.com
KexAlgorithms +diffie-hellman-group14-sha1
MACs +hmac-sha1
HostKeyAlgorithms +ssh-rsa
PubkeyAcceptedKeyTypes +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa
("PubkeyAcceptedKeyTypes" and "PubkeyAcceptedAlgorithms"
have identical meaning; the former is the old option name, the latter is the
new one. Virt-v2v uses both "libssh" and "ssh" when
converting a guest from Xen, and on some operating systems, "libssh"
and "ssh" may not both accept the same option variant.)
When connecting to RHEL 5 sshd from RHEL 9, the SHA1 algorithm's use in
signatures has to be re-enabled at the OpenSSL level, in addition to the above
SSH configuration. Create a file called
$HOME/openssl-sha1.cnf with the following contents:
.include /etc/ssl/openssl.cnf
[openssl_init]
alg_section = evp_properties
[evp_properties]
rh-allow-sha1-signatures = yes
and export the following variable into the environment of the
"virt-v2v" process:
OPENSSL_CONF=$HOME/openssl-sha1.cnf
Note that the "OPENSSL_CONF" environment variable will only take
effect if the libvirt client library used by virt-v2v is at least version
8.6.0.
Use the
virsh(1) command to list the guests on the remote Xen host:
$ virsh -c xen+ssh://[email protected] list --all
Id Name State
----------------------------------------------------
0 Domain-0 running
- rhel49-x86_64-pv shut off
You should also try dumping the metadata from any guest on your server, like
this:
$ virsh -c xen+ssh://[email protected] dumpxml rhel49-x86_64-pv
<domain type='xen'>
<name>rhel49-x86_64-pv</name>
[...]
</domain>
If the above commands do not work, then virt-v2v is not going to work
either. Fix your libvirt configuration or the remote server before
continuing.
If the guest disks are located on a host block device, then the
conversion will fail. See "Xen or ssh conversions from block
devices" below for a workaround.
To import a particular guest from a Xen server, do:
$ virt-v2v -ic 'xen+ssh://[email protected]' \
rhel49-x86_64-pv \
-o local -os /var/tmp
where "rhel49-x86_64-pv" is the name of the guest (which must be shut
down).
In this case the output flags are set to write the converted guest to a
temporary directory as this is just an example, but you can also write to
libvirt or any other supported target.
Currently virt-v2v cannot directly access a Xen guest (or any guest located
remotely over ssh) if that guest’s disks are located on host block
devices.
To tell if a Xen guest uses host block devices, look at the guest XML. You will
see:
<disk type='block' device='disk'>
...
<source dev='/dev/VG/guest'/>
where "type='block'", "source dev=" and "/dev/..."
are all indications that the disk is located on a host block device.
This happens because the qemu ssh block driver that we use to access remote
disks uses the ssh sftp protocol, and this protocol cannot correctly detect
the size of host block devices.
The workaround is to copy the block device from the remote Xen server to a
regular local file, copy the libvirt guest XML, adjust the "disk"
element to point to the local file, and use "-i libvirtxml" mode
instead.
virt-v2v(1).
Richard W.M. Jones
Copyright (C) 2009-2020 Red Hat Inc.
To get a list of bugs against libguestfs, use this link:
https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
To report a new bug against libguestfs, use this link:
https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
When reporting a bug, please supply:
- •
- The version of libguestfs.
- •
- Where you got libguestfs (eg. which Linux distro, compiled
from source, etc)
- •
- Describe the bug accurately and give a way to reproduce
it.
- •
- Run libguestfs-test-tool(1) and paste the
complete, unedited output into the bug report.