Troubleshoot Compute¶

Problem¶

Missing credentials cause a 403 forbidden error.

Solution¶

To resolve this issue, use one of these methods:

1. Manual method

   Gets the novarc file from the project ZIP file, saves existing credentials in case of override, and manually sources the novarc file.

2. Script method

   Generates novarc from 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 novarc creation.

Problem¶

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.

Solution¶

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 under /var/lib/nova/instances on the nova-compute host and make sure that these files are present:

• libvirt.xml
• disk
• disk-raw
• kernel
• ramdisk
• console.log, after the instance starts.

If any files are missing, empty, or very small, the nova-compute service did not successfully download the images from the Image service.

Also check nova-compute.log for exceptions. Sometimes they do not appear in the console output.

Next, check the log file for the instance in the /var/log/libvirt/qemu 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

Problem¶

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.

Solution¶

To rectify this, append the following parameters to kernel arguments specified in the instance's boot loader:

console=tty0 console=ttyS0,115200n8

Upon rebooting, the instance will be configured to send output to the Compute service.

Problem¶

Instances can remain in an intermediate state, such as deleting.

Solution¶

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

Problem¶

Instances may boot slowly, or do not boot. File injection can cause this problem.

Solution¶

To disable injection in libvirt, set the following in nova.conf:

[libvirt]
inject_partition = -2

Problem¶

Administrators using libvirt version 1.2.2 may experience problems with live snapshot creation. Occasionally, libvirt version 1.2.2 fails to create live snapshots under the load of creating concurrent snapshot.

Solution¶

To effectively disable the libvirt live snapshotting, until the problem is resolved, configure the disable_libvirt_livesnapshot option. You can turn off the live snapshotting mechanism by setting up its value to True in the [workarounds] section of the nova.conf file:

[workarounds]
disable_libvirt_livesnapshot = True

Problem¶

When you attempt to create a VM, the error shows the VM is in the BUILD then ERROR state.

Solution¶

On the KVM host, run cat /proc/cpuinfo. Make sure the vmx or 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.

Problem¶

Failed to attach a volume after detaching the same volume.

Solution¶

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 vdb, vdc, or vdd device names:

# ls -al /dev/disk/by-path/
total 0
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.

Problem¶

This warning and error occurs if you do not have the required sysfsutils 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\
7a-be9b-47c97626555c]
Failed to attach volume 13d5c633-903a-4764-a5a0-3336945b1db1 at /dev/vdk.

Solution¶

Install the sysfsutils package on the compute node. For example:

# apt-get install sysfsutils

Problem¶

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\
6c7-c1e3-4bf0-8ef0-f07aa4c3d5f3|instance: 60ebd6c7-c1e3-4bf0-8ef0-f07aa4c3\
d5f3]
Failed to connect to volume 6f6a6a9c-dfcf-4c8d-b1a8-4445ff883200 while\
attaching at /dev/vdjTRACE nova.compute.manager [instance: 60ebd6c7-c1e3-4\
bf0-8ef0-f07aa4c3d5f3|instance: 60ebd6c7-c1e3-4bf0-8ef0-f07aa4c3d5f3]
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)

Solution¶

The network administrator must configure the FC SAN fabric by correctly zoning the WWN (port names) from your compute node HBAs.

Problem¶

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)

Solution¶

Install the multipath-tools package on the compute node. For example:

# apt-get install multipath-tools

Problem¶

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'

Solution¶

Install the sg3-utils package on the compute node. For example:

# apt-get install sg3-utils