[Openstack-operators] rbd ephemeral storage, very slow deleting...

Chris Friesen chris.friesen at windriver.com
Wed Sep 24 22:25:24 UTC 2014

On 09/24/2014 02:43 PM, Scott Kohler wrote:
> On 09/24/2014 04:29 PM, Abel Lopez wrote:
>> This is expected behavior, unfortunately.
>> I spoke to the ceph guys about this last year. When you delete an ‘image’ from a pool, the monitors (IIRC) don’t instantly know where all the segments are across all the OSDs, so it takes a while to find/delete each one.
> We also saw this, and were especially alarmed at the high CPU load on
> deletion. So we came up with a work-around that also makes for very fast
> instance creation as well as deletion, if you are using Ceph:
> Create a volume from the image first, then create an instance from that
> bootable volume. Volume creation/deletion is quite fast, with down side
> of a two-step process. We have a CLI script that has an instance up and
> ssh-able in less than 4 minutes, including volume creation. booting and
> selinux recalc on first boot. Deletes take about 30 seconds. FWIW.

Presumably the resource reclamation time is affected by the volume_clear 
setting and volume size?  I'm guessing it'd take longer than 30 seconds 
to zero out a large volume.


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