On 12/21/2015 04:50 PM, Josh Durgin wrote: > On 12/21/2015 07:09 AM, Jason Dillaman wrote: >> You will have to ensure that your writes are properly aligned with the >> object size (or object set if fancy striping is used on the RBD >> volume). In that case, the discard is translated to remove operations >> on each individual backing object. The only time zeros are written to >> disk is if you specify an offset somewhere in the middle of an object >> (i.e. the whole object cannot be deleted nor can it be truncated) -- >> this is the partial discard case controlled by that configuration param. >> > > I'm curious what's using the virVolWipe stuff - it can't guarantee it's > actually wiping the data in many common configurations, not just with > ceph but with any kind of disk, since libvirt is usually not consuming > raw disks, and with modern flash and smr drives even that is not enough. > There's a recent patch improving the docs on this [1]. > > If the goal is just to make the data inaccessible to the libvirt user, > removing the image is just as good. > > That said, with rbd there's not much cost to zeroing the image with > object map enabled - it's effectively just doing the data removal step > of 'rbd rm' early. > I was looking at the features the RBD storage pool driver is missing in libvirt and it is: - Build from Volume. That's RBD cloning - Uploading and Downloading Volume - Wiping Volume The thing about wiping in libvirt is that the volume still exists afterwards, it is just empty. My discard code now works, but I wanted to verify. If I understand Jason correctly it would be a matter of figuring out the 'order' of a image and call rbd_discard in a loop until you reach the end of the image. I just want libvirt to be as feature complete as possible when it comes to RBD. Wido > Josh > > [1] http://comments.gmane.org/gmane.comp.emulators.libvirt/122235 > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Wido den Hollander 42on B.V. Ceph trainer and consultant Phone: +31 (0)20 700 9902 Skype: contact42on -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
