Cannot create a volume from a VMDK image

Issue

• Our vendor provided a CentOS VMDK image to us. In order to upload this image to our OpenStack platform, I have done the following tasks:

1. Convert the VMDK image to a single file version by the command: vmware-vdiskmanager -r Directory\sas-centos6.vmdk -t 0 sas-centos.vmdk
2. Upload this sas-centos.vmdk to our OpenStack NAS server.
3. Use glance to import the image to cinder:

glance image-create --name “centos" \
        --is-public true \
        --disk-format vmdk \
        --container-format bare \
        --file /var/tmp/centos.vmdk

• The image was successfully uploaded. However, when I tried to create a disk volume from this image file on our OpenStack web page, an error was returned after a long period of waiting.