Welcome to the Free Software contributions diary of Loïc Dachary. Although the posts look like blog entries, they really are technical reports about the work done during the day. They are meant to be used as a reference by co-developers and managers.

Create a partition and make it an OSD

Note: it is similar to Creating a Ceph OSD from a designated disk partition but simpler.
In a nutshell, to use the remaining space from /dev/sda and assuming Ceph is already configured in /etc/ceph/ceph.conf it is enough to:

$ sgdisk --largest-new=$PARTITION --change-name="$PARTITION:ceph data" \
  --partition-guid=$PARTITION:$OSD_UUID \
  --typecode=$PARTITION:$PTYPE_UUID -- /dev/sda
$ partprobe
$ ceph-disk prepare /dev/sda$PARTITION
$ ceph-disk activate /dev/sda$PARTITION

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Posted in ceph | Leave a comment

enable secondary network interface and ignore the default route

When two network interfaces are associated to an OpenStack instance, the Ubuntu precise guest will only configure the first one. Assuming the second can be configured via DHCP, it can be added with:

cat > /etc/network/interfaces.d/eth1.cfg <<EOF
auto eth1
iface eth1 inet dhcp
EOF

If the DHCP server answering on eth1 provides a default gateway, it will override the gateway provided by the DHCP server answering on eth0. The routers request can be removed from the list of default requests in /etc/dhcp/dhclient.conf

request subnet-mask, broadcast-address, time-offset,
        domain-name, domain-name-servers, domain-search, host-name,
        netbios-name-servers, netbios-scope, interface-mtu,
        rfc3442-classless-static-routes, ntp-servers,
        dhcp6.domain-search, dhcp6.fqdn,
        dhcp6.name-servers, dhcp6.sntp-servers;

It can then be re-activated only for eth0

echo 'interface "eth0" { request routers; }' >> /etc/dhcp/dhclient.conf
Posted in Havana, openstack | Leave a comment

Recovering from a cinder RBD host failure

OpenStack Havana Cinder volumes associated with a RBD Ceph pool are bound to a host.

cinder service-list --host bm0014.the.re@rbd-ovh
+---------------+-----------------------+------+---------+-------+
|     Binary    |          Host         | Zone |  Status | State |
+---------------+-----------------------+------+---------+-------+
| cinder-volume | bm0014.the.re@rbd-ovh | ovh  | enabled |   up  |
+---------------+-----------------------+------+---------+-------+

A volume created on this host is permanently associated with it:

$ mysql -e "select host from volumes where deleted = 0 and display_name = 'nerrant.fr'" cinder
+-----------------------+
| host                  |
+-----------------------+
| bm0014.the.re@rbd-ovh |
+-----------------------+

If the host fails, any attempt to detach the volume will fail because the cinder-api cannot reach the host:

/var/log/cinder/cinder-api.log
2014-05-04 17:50:59.928 15128 TRACE cinder.api.middleware.fault Timeout: Timeout while
   waiting on RPC response - topic: "cinder-volume:bm0014.the.re@rbd-ovh",
   RPC method: "terminate_connection" info: ""

The failed cinder host is first disabled so the scheduler will no longer try to access it:

cinder service-disable bm0014.the.re cinder-volume

The database is updated with another host configured with access to the same Ceph pool.

$ mysql -e "update volumes set host = 'bm0015.the.re@rbd-ovh' \
   where deleted = 0 and display_name = 'nerrant.fr'" cinder
Posted in Havana, ceph, openstack | 3 Comments

Non profit OpenStack & Ceph cluster distributed over five datacenters

A few non profit organizations (April, FSF France, tetaneutral.net…) and volunteers constantly research how to get compute, storage and bandwidth that are:

  • 100% Free Software
  • Content neutral
  • Low maintenance
  • Reliable
  • Cheap

The latest setup, in use since ocbober 2013, is based on a Ceph and OpenStack cluster spread over five datacenters. It has been designed for the following use cases:

  • Free Software development and continuous integration
  • Hosting low activity web sites, mail servers etc.
  • Keeping backups
  • Sharing movies and music

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Posted in Havana, ceph, openstack | 4 Comments

Fixing OpenVSwitch and GRE asymetric performances

OpenStack Havana is configured to use OpenVSwitch 1.10.2 as packaged for Ubuntu precise, with a linux-3.11 kernel.The cluster is connected to a 100Mb/s link. When sending data from an instance to the internet (using iperf), it shows ~90Mb/s. When receiving data from the internet to the instance, it is down to ~1Mb/s. After capturing the packets on the interface used by the default route on the hypervisor running the neutron router with

tcpdump -i eth0 host 91.224.149.132 -w /tmp/bad.cap

wireshark /tmp/bad.cap shows a lot of retransmissions.

A similar problem was reported back in October 2013 and hints that it may be a kernel problem. Upgrading the kernel of the hypervisor running the neutron router to linux-3.13 indeed fixes the problem. The compute nodes running the instances do not need their kernel updated, they can keep using the linux-3.11 kernel with the 1.10.2 version of the OpenVSwitch datapath kernel module. The OpenVSwitch kernel part is in the linux-3.13 tree and the openvswitch-datapath-dkms is not used any longer. It will fail to compile against the linux-3.13 headers but the error can be ignored and the package uninstalled.

Posted in Havana, openstack | 8 Comments

Two minor pitfalls when upgrading Havana stable

When upgrading an OpenStack compute or l3 agent node from 1:2013.2 to 1:2013.2.3 on Ubuntu precise 12.04.4:

  • The nova-compute version 1:2013.2 is expected to fail with
    /var/log/nova/nova-compute.log
    IncompatibleObjectVersion: Version 1.9 of Instance is not supported
    

    when interfaced with a 1:2013.2.3. It will not disrupt the running instances but will prevent operations on them until the upgrade is complete.

  • neutron-l3-agent will fail with:

    /var/log/neutron/metadata-agent.log
    AttributeError: 'HTTPClient' object has no attribute 'auth_tenant_id'
    

    because the python-neutronclient package must also be upgraded . It only happens if upgrading with apt-get install neutron-common but will be fine if upgrading with apt-get dist-upgrade.

Posted in Havana, openstack | Leave a comment

Reseting an instance {power,vm,task}_state in Havana

Sometime, after an hypervisor crash or nova-compute error, an OpenStack instance can be left in a state that cannot be conveniently fixed with nova reset-state.

$ nova list
+--------------------------------------+----------------+---------+...
| ID                                   | Name           | Status  |
+--------------------------------------+----------------+---------+...
| ca9496e9-0bd2-4734-9cf9-eb4e264628f7 | www            | SHUTOFF |
+--------------------------------------+----------------+---------+...
...  -------------+-------------+----------------------------------+
      Task State  | Power State | Networks                         |
...  -------------+-------------+----------------------------------+
      powering-on | Shutdown    | fsf-lan=10.0.3.18, 93.20.168.177 |
...  -------------+-------------+----------------------------------+

Setting the fields for the instance directly in the database will allow operations on the instance (nova start or nova volume-detach for instance):

$ mysql -e "update instances set task_state = NULL, \
           vm_state = 'stopped', \
           power_state = 4 \
           where deleted = 0 and hostname = 'www' and \
           uuid = 'ca9496e9-0bd2-4734-9cf9-eb4e264628f7'" nova

Using the uuid is necessary to avoid modifying an unrelated instance with the same name. This should be done only after verifying that the instance does not exist on the hypervisor with:

$ ps -fauwwwx | grep ca9496e9-0bd2-4734-9cf9-eb4e264628f7
Posted in Havana, openstack | Leave a comment

Sharing hard drives with Ceph

A group of users give hard drives to the system administrator of the Ceph cluster. In exchange, each of them get credentials to access a dedicated pool of a given size from the Ceph cluster.
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Posted in ceph | 4 Comments

Working on a patch series with gerrit

A small patch series (1, 2, 3) is worked on in the wip-key-inject-unless topic branch.

When running git review –yes, each commit is dispatched to the review designated by the Change-Id: of the message.
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Posted in gerrit, openstack | Leave a comment

HOWTO migrate an AMI from Essex to a bootable volume on Havana

A snapshot of an Essex OpenStack instance contains an AMI ext3 file system. It is rsync’ed to a partitioned volume in the Havana cluster. After installing grub from chroot, a new instance can be booted from the volume.
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Posted in Essex, Havana, openstack | 1 Comment