On Tue, Jun 24, 2014 at 9:42 AM, Avishay Traeger <avis...@stratoscale.com> wrote:
> One more reason why block storage management doesn't really work on file > systems. I'm OK with storing the format, but that just means you fail > migration/backup operations with different formats, right? > +1... sooooo nice that somebody else said it for me this time!! We need to make sure this is completely abstracted from end-user and the manager can make the right decisions (ie implement a way to work from one to the other). > > > On Mon, Jun 23, 2014 at 6:07 PM, Trump.Zhang <zhangleiqi...@gmail.com> > wrote: > >> Hi, all: >> >> Currently, there are several filesystem-based drivers in Cinder, such >> as nfs, glusterfs, etc. Multiple format of volume other than "raw" can be >> potentially supported in these drivers, such as qcow2, raw, sparse, etc. >> >> However, Cinder does not store the actual format of volume and >> suppose all volumes are "raw" format. It will has or already has several >> problems as follows: >> >> 1. For volume migration, the generic migration implementation in >> Cinder uses the "dd" command to copy "src" volume to "dest" volume. If the >> src volume is "qcow2" format, instance will not get the right data from >> volume after the dest volume attached to instance, because the info >> returned from Cinder states that the volume's format is "raw" other than >> "qcow2" >> 2. For volume backup, the backup driver also supposes that src >> volumes are "raw" format, other format will not be supported >> >> Indeed, glusterfs driver has used "qemu-img info" command to judge >> the format of volume. However, as the comment from Duncan in [1] says, this >> auto detection method has many possible error / exploit vectors. Because if >> the beginning content of a "raw" volume happens to a "qcow2" disk, auto >> detection method will judge this volume to be a "qcow2" volume wrongly. >> >> I proposed that the "format" info should be added to "admin_metadata" >> of volumes, and enforce it on all operations, such as create, copy, migrate >> and retype. The "format" will be only set / updated for filesystem-based >> drivers, other drivers will not contains this metadata and have a default >> "raw" format. >> >> Any advice? >> >> [1] https://review.openstack.org/#/c/100529/ >> >> -- >> ------------------- >> Best Regards >> >> Trump.Zhang >> >> _______________________________________________ >> OpenStack-dev mailing list >> OpenStack-dev@lists.openstack.org >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > >
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