I've got Cinder running atop an LVM volume group as described in the install guide. Everything works -- creating, attaching, detaching, deleting, etc.

However, upon deleting a 100GB Cinder volume, I noticed it took quite a long time due to zeroing out the bits on disk to prevent data leak once an overlapping volume gets created. The first test took about ~11 minutes for this step to complete.

I'd definitely like to speed this up a bit, if possible. I've tried adjusting the volume_dd_blocksize option in /etc/cinder/cinder.conf from the default 1M to 4M, and restarted all Cinder services. However, creating then deleting a volume still yields the same block size being used when it gets wiped (dd ... bs=1M).

Is there some other place this option needs to go? My configuration currently consists of:

[DEFAULT]
rootwrap_config = /etc/cinder/rootwrap.conf
api_paste_confg = /etc/cinder/api-paste.ini
debug = True
verbose = True
auth_strategy = keystone
state_path = /var/lib/cinder
lock_path = /var/lock/cinder

# MySQL Connection #
sql_connection=mysql://cinder:111p455w0rd@10.1.2.3/cinder

# RabbitMQ #
rabbit_password=111p455w0rd

# iSCSI and Volume Management #
iscsi_helper = tgtadm
iscsi_ip_address = 10.90.18.152
volume_name_template = volume-%s
volume_group = cinder-volumes
volume_dd_blocksize = 4M