Re: [libvirt] [PATCH 5/5] storage: Add helper to compare logical pool def against pvs output

On Wed, Dec 16, 2015 at 07:46:18AM -0500, John Ferlan wrote: > > > On 12/16/2015 07:02 AM, Ján Tomko wrote: >> On Mon, Dec 07, 2015 at 03:47:58PM -0500, John Ferlan wrote: >>> https://bugzilla.redhat.com/show_bug.cgi?id=1025230 >>> >>> Add a new helper virStorageBackendLogicalMatchPoolSource to compare the >>> pool's source name against the output from a 'pvs' command to list all >>> volume group physical volume data on the host. In addition, compare the >>> pool's source device list against the particular volume group's device >>> list to ensure the source device(s) listed for the pool match what the >>> was listed for the volume group. >>> >>> Then for pool startup or check API's we need to call this new API in >>> order to ensure that the pool we're about to start or declare active >>> during checkPool has a valid definition vs. the running host. >>> >> >> This patch breaks starting of logical pools with no source devices. >> >> Jan >> > > Not enough information for me to go on... Can you provide sample XML > that works prior to the change? From just your description I assume you > mean: > > <source> > <name>xxx</name> > <format type='lvm2'/> > </source> > In my case it's: <source> <name>vg</name> <format type='unknown'/> </source> <target> <path>/dev/vg</path> ... </target> (Also, if the vg_name matches the pool name, the whole <source> element can be omitted)

> instead of having a > > <device path='/dev/sde'/> > > As the source device > > Without a source device how would pool-build work (vgcreate)? It would not, and pool-build is the only time when the list of physical volumes is required. Libvirt also uses the list for pool-delete, but this is IMO a bug, considering that we do not keep this list up to date and it could end up calling pvremove on PVs that are no longer a part of that VG. Thinking about it some more, the point of LVM is to abstract from the physical volumes, so I do not think we should burden the user with the task of updating the pool's XML every time the underlying PVs change (i.e. the USB hard drives were plugged in in a different order). Instead of logging a warning / rejecting the pool, could we update the source devices list on pool refresh?

Jan