Failed to create a volume during volume exercise

[Itzik Brown]

Happened once:

http://logs.openstack.org/93/59093/3/check/check-grenade-dsvm/4c302d2/console.html

2013-12-08 15:50:53.441 | + cinder create --display_name ex-vol-739f2dd3 --display_description 'test volume: ex-vol-739f2dd3' 1
2013-12-08 15:50:54.413 | +-------------------+--------------------------------------+
2013-12-08 15:50:54.413 | | Property | Value |
2013-12-08 15:50:54.413 | +-------------------+--------------------------------------+
2013-12-08 15:50:54.413 | | attachments | [] |
2013-12-08 15:50:54.414 | | availability_zone | nova |
2013-12-08 15:50:54.414 | | bootable | false |
2013-12-08 15:50:54.414 | | created_at | 2013-12-08T15:50:54.000000 |
2013-12-08 15:50:54.414 | | description | test volume: ex-vol-739f2dd3 |
2013-12-08 15:50:54.414 | | id | 00c9f1c6-650c-4935-bdce-5394dcdbe696 |
2013-12-08 15:50:54.414 | | metadata | {} |
2013-12-08 15:50:54.414 | | name | ex-vol-739f2dd3 |
2013-12-08 15:50:54.415 | | size | 1 |
2013-12-08 15:50:54.415 | | snapshot_id | None |
2013-12-08 15:50:54.415 | | source_volid | None |
2013-12-08 15:50:54.415 | | status | creating |
2013-12-08 15:50:54.415 | | user_id | e730224094b141da954e15bb19424120 |
2013-12-08 15:50:54.415 | | volume_type | None |
2013-12-08 15:50:54.415 | +-------------------+--------------------------------------+
2013-12-08 15:50:54.445 | + timeout 90 sh -c 'while ! cinder list | grep ex-vol-739f2dd3 | grep available; do sleep 1; done'
2013-12-08 15:52:24.448 | + die 162 'Volume ex-vol-739f2dd3 not created'
2013-12-08 15:52:24.448 | + local exitcode=0
2013-12-08 15:52:24.448 | + set +o xtrace
2013-12-08 15:52:24.448 | [Call Trace]
2013-12-08 15:52:24.448 | /opt/stack/new/devstack/exercises/volumes.sh:162:die
2013-12-08 15:52:24.486 | [ERROR] /opt/stack/new/devstack/exercises/volumes.sh:162 Volume ex-vol-739f2dd3 not created