Common problems for Compute typically involve misconfigured networking or credentials that are not sourced properly in the environment. Also, most flat networking configurations do not enable ping or ssh from a compute node to the instances that run on that node. Another common problem is trying to run 32-bit images on a 64-bit compute node. This section shows you how to troubleshoot Compute.
Move the sections below into sub-pages for readability.
Compute service logging¶
Compute stores a log file for each service in
/var/log/nova. For example,
nova-compute.log is the log for the
nova-compute service. You can set
the following options to format log strings for the
nova.log module in the
If the log level is set to
debug, you can also specify
logging_debug_format_suffix to append extra formatting. For information
about what variables are available for the formatter, see Formatter Objects.
You have two logging options for OpenStack Compute based on configuration
nova.conf, include the
logfile option to enable logging.
Alternatively you can set
use_syslog = 1 so that the nova daemon logs to
Guru Meditation reports¶
A Guru Meditation report is sent by the Compute service upon receipt of the
SIGUSR2 signal (
SIGUSR1 before Mitaka). This report is a
general-purpose error report that includes details about the current state of
the service. The error report is sent to
For example, if you redirect error output to
nova-api 2>/var/log/nova/nova-api-err.log, resulting in the process
ID 8675, you can then run:
# kill -USR2 8675
This command triggers the Guru Meditation report to be printed to
The report has the following sections:
Package: Displays information about the package to which the process belongs, including version information.
Threads: Displays stack traces and thread IDs for each of the threads within the process.
Green Threads: Displays stack traces for each of the green threads within the process (green threads do not have thread IDs).
Configuration: Lists all configuration options currently accessible through the CONF object for the current process.
For more information, see Guru Meditation Reports.
Common errors and fixes for Compute¶
The ask.openstack.org site offers a place to ask and answer questions, and you can also mark questions as frequently asked questions. This section describes some errors people have posted previously. Bugs are constantly being fixed, so online resources are a great way to get the most up-to-date errors and fixes.
Credential errors, 401, and 403 forbidden errors¶
Missing credentials cause a
403 forbidden error.
To resolve this issue, use one of these methods:
novarcfile from the project ZIP file, saves existing credentials in case of override, and manually sources the
novarcfrom the project ZIP file and sources it for you.
When you run
nova-api the first time, it generates the certificate
authority information, including
openssl.cnf. If you start the CA services
before this, you might not be able to create your ZIP file. Restart the
services. When your CA information is available, create your ZIP file.
Also, check your HTTP proxy settings to see whether they cause problems with
Live migration permission issues¶
When live migrating an instance, you may see errors like the below:
libvirtError: operation failed: Failed to connect to remote libvirt URI
qemu+ssh://stack@cld6b16/system: Cannot recv data: Host key verification
failed.: Connection reset by peer
Ensure you have completed all the steps outlined in
Configure SSH between compute nodes. In particular, it’s important to note
libvirt process runs as
root even though it may be connecting
to a different user (
stack in the above example). You can ensure everything
is correctly configured by attempting to connect to the remote host via the
root user. Using the above example once again:
$ su - -c 'ssh stack@cld6b16'
Sometimes a particular instance shows
pending or you cannot SSH to it.
Sometimes the image itself is the problem. For example, when you use flat
manager networking, you do not have a DHCP server and certain images do not
support interface injection; you cannot connect to them.
To fix instance errors use an image that does support this method, such as Ubuntu, which obtains an IP address correctly with FlatManager network settings.
To troubleshoot other possible problems with an instance, such as an instance
that stays in a spawning state, check the directory for the particular instance
/var/lib/nova/instances on the
nova-compute host and make sure
that these files are present:
console.log, after the instance starts.
If any files are missing, empty, or very small, the
did not successfully download the images from the Image service.
nova-compute.log for exceptions. Sometimes they do not appear in
the console output.
Next, check the log file for the instance in the
directory to see if it exists and has any useful error messages in it.
Finally, from the
/var/lib/nova/instances directory for the instance, see
if this command returns an error:
# virsh create libvirt.xml
Empty log output for Linux instances¶
You can view the log output of running instances from either the Log tab of the dashboard or the output of nova console-log. In some cases, the log output of a running Linux instance will be empty or only display a single character (for example, the ? character).
This occurs when the Compute service attempts to retrieve the log output of the instance via a serial console while the instance itself is not configured to send output to the console.
To rectify this, append the following parameters to kernel arguments specified in the instance’s boot loader:
Upon rebooting, the instance will be configured to send output to the Compute service.
Reset the state of an instance¶
Instances can remain in an intermediate state, such as
You can use the nova reset-state command to manually reset the state of an instance to an error state. You can then delete the instance. For example:
$ nova reset-state c6bbbf26-b40a-47e7-8d5c-eb17bf65c485
$ openstack server delete c6bbbf26-b40a-47e7-8d5c-eb17bf65c485
You can also use the
--active parameter to force the instance back to an
active state instead of an error state. For example:
$ nova reset-state --active c6bbbf26-b40a-47e7-8d5c-eb17bf65c485
Instances may boot slowly, or do not boot. File injection can cause this problem.
To disable injection in libvirt, set the following in
inject_partition = -2
If you have not enabled the config drive and you want to make user-specified files available from the metadata server for to improve performance and avoid boot failure if injection fails, you must disable injection.
Cannot find suitable emulator for x86_64¶
When you attempt to create a VM, the error shows the VM is in the
On the KVM host, run cat /proc/cpuinfo. Make sure the
svm flags are set.
Follow the instructions in the Enable KVM section in the Nova Configuration Reference to enable hardware virtualization support in your BIOS.
Failed to attach volume after detaching¶
Failed to attach a volume after detaching the same volume.
You must change the device name on the nova-attach command. The VM
might not clean up after a nova-detach command runs. This example
shows how the nova-attach command fails when you use the
vdd device names:
# ls -al /dev/disk/by-path/
drwxr-xr-x 2 root root 200 2012-08-29 17:33 .
drwxr-xr-x 5 root root 100 2012-08-29 17:33 ..
lrwxrwxrwx 1 root root 9 2012-08-29 17:33 pci-0000:00:04.0-virtio-pci-virtio0 -> ../../vda
lrwxrwxrwx 1 root root 10 2012-08-29 17:33 pci-0000:00:04.0-virtio-pci-virtio0-part1 -> ../../vda1
lrwxrwxrwx 1 root root 10 2012-08-29 17:33 pci-0000:00:04.0-virtio-pci-virtio0-part2 -> ../../vda2
lrwxrwxrwx 1 root root 10 2012-08-29 17:33 pci-0000:00:04.0-virtio-pci-virtio0-part5 -> ../../vda5
lrwxrwxrwx 1 root root 9 2012-08-29 17:33 pci-0000:00:06.0-virtio-pci-virtio2 -> ../../vdb
lrwxrwxrwx 1 root root 9 2012-08-29 17:33 pci-0000:00:08.0-virtio-pci-virtio3 -> ../../vdc
lrwxrwxrwx 1 root root 9 2012-08-29 17:33 pci-0000:00:09.0-virtio-pci-virtio4 -> ../../vdd
lrwxrwxrwx 1 root root 10 2012-08-29 17:33 pci-0000:00:09.0-virtio-pci-virtio4-part1 -> ../../vdd1
You might also have this problem after attaching and detaching the same volume from the same VM with the same mount point multiple times. In this case, restart the KVM host.
Failed to attach volume, systool is not installed¶
This warning and error occurs if you do not have the required
package installed on the compute node:
WARNING nova.virt.libvirt.utils [req-1200f887-c82b-4e7c-a891-fac2e3735dbb\
admin admin|req-1200f887-c82b-4e7c-a891-fac2e3735dbb admin admin] systool\
is not installed
ERROR nova.compute.manager [req-1200f887-c82b-4e7c-a891-fac2e3735dbb admin\
admin|req-1200f887-c82b-4e7c-a891-fac2e3735dbb admin admin]
[instance: df834b5a-8c3f-477a-be9b-47c97626555c|instance: df834b5a-8c3f-47\
Failed to attach volume 13d5c633-903a-4764-a5a0-3336945b1db1 at /dev/vdk.
sysfsutils package on the compute node. For example:
# apt-get install sysfsutils
Failed to connect volume in FC SAN¶
The compute node failed to connect to a volume in a Fibre Channel (FC) SAN configuration. The WWN may not be zoned correctly in your FC SAN that links the compute host to the storage array:
ERROR nova.compute.manager [req-2ddd5297-e405-44ab-aed3-152cd2cfb8c2 admin\
demo|req-2ddd5297-e405-44ab-aed3-152cd2cfb8c2 admin demo] [instance: 60ebd\
Failed to connect to volume 6f6a6a9c-dfcf-4c8d-b1a8-4445ff883200 while\
attaching at /dev/vdjTRACE nova.compute.manager [instance: 60ebd6c7-c1e3-4\
Traceback (most recent call last):...f07aa4c3d5f3\] ClientException: The\
server has either erred or is incapable of performing the requested\
operation.(HTTP 500)(Request-ID: req-71e5132b-21aa-46ee-b3cc-19b5b4ab2f00)
The network administrator must configure the FC SAN fabric by correctly zoning the WWN (port names) from your compute node HBAs.
Multipath call failed exit¶
Multipath call failed exit. This warning occurs in the Compute log if you do
not have the optional
multipath-tools package installed on the compute
node. This is an optional package and the volume attachment does work without
the multipath tools installed. If the
multipath-tools package is installed
on the compute node, it is used to perform the volume attachment. The IDs in
your message are unique to your system.
WARNING nova.storage.linuxscsi [req-cac861e3-8b29-4143-8f1b-705d0084e571 \
admin admin|req-cac861e3-8b29-4143-8f1b-705d0084e571 admin admin] \
Multipath call failed exit (96)
multipath-tools package on the compute node. For example:
# apt-get install multipath-tools
Failed to Attach Volume, Missing sg_scan¶
Failed to attach volume to an instance,
sg_scan file not found. This error
occurs when the sg3-utils package is not installed on the compute node. The
IDs in your message are unique to your system:
ERROR nova.compute.manager [req-cf2679fd-dd9e-4909-807f-48fe9bda3642 admin admin|req-cf2679fd-dd9e-4909-807f-48fe9bda3642 admin admin]
[instance: 7d7c92e0-49fa-4a8e-87c7-73f22a9585d5|instance: 7d7c92e0-49fa-4a8e-87c7-73f22a9585d5]
Failed to attach volume 4cc104c4-ac92-4bd6-9b95-c6686746414a at /dev/vdcTRACE nova.compute.manager
[instance: 7d7c92e0-49fa-4a8e-87c7-73f22a9585d5|instance: 7d7c92e0-49fa-4a8e-87c7-73f22a9585d5]
Stdout: '/usr/local/bin/nova-rootwrap: Executable not found: /usr/bin/sg_scan'
sg3-utils package on the compute node. For example:
# apt-get install sg3-utils
Requested microversions are ignored¶
When making a request with a microversion beyond 2.1, for example:
$ openstack --os-compute-api-version 2.15 server group create \
--policy soft-anti-affinity my-soft-anti-group
It fails saying that “soft-anti-affinity” is not a valid policy, even thought it is allowed with the 2.15 microversion.
compute endpoint in the identity service catalog is pointing
/v2.1 instead of
/v2. The former route supports microversions,
while the latter route is considered the legacy v2.0 compatibility-mode
route which renders all requests as if they were made on the legacy v2.0 API.