Michael DeHaan wrote: > Cole Robinson wrote: >> Michael DeHaan wrote: >> >>> Chris Lalancette wrote: >>> >>>> Michael DeHaan wrote: >>>> >>>> >>>>> I had a user question about how they can specify blktap for Xen in >>>>> Cobbler instead of the file driver (for performance reasons) ... well, >>>>> it turns out they can't (yet). >>>>> >>>>> Under what conditions can we use blktap, and is that advisable? (I had >>>>> thought this might work like virtio, in which case, passing in the os >>>>> version uses a table, but it seems this may only actually depend on the >>>>> host and has no guest limitations?) >>>>> >>>>> >>>> That's exactly right. It's a property of how the host OS accesses the disk on >>>> behalf of the domain, not of how the disk is presented to the domain. In fact, >>>> for Xen PV domains, you should *only* ever use blktap (i.e. tap:aio:); direct >>>> file: access can corrupt your guest domains on host crash. The situation with >>>> FV domains is more complicated, but there, you can use file:, since it properly >>>> does flushing. >>>> >>>> >>>> >>> >>>>> It looks like from the virtinst code I could just call >>>>> utils.is_blktap_capable() from my libvirt-using application and if so, >>>>> then pass the driver=DRIVER_TAP options to virstinst. >>>>> >>>>> Good idea? Bad idea? >>>>> >>>>> >>>> The only reasonable default for Xen PV domains, in my opinion. >>>> >>>> >>>> >>> Thanks. >>> >>> FWIW the default behavior of python-virtinst seems to be to /not/ use >>> blktap, and should probably be fixed then if there's a potential >>> corruption problem. >>> >>> I haven't tested command line virt-install to see what it does. >>> >>> >> That default is actually set in virt-install and virt-manager, but >> probably should have been moved into the virtinst library a long time ago. >> >> - COle >> > > Yeah, I can't keep up very well when stuff doesn't happen there :) > > Should I make the fix in koan also or do you want to move it? > > --Michael > I'll take a look at moving it into the library, but for back compat it wouldn't hurt to set the default in koan. The virt-install code is: http://hg.et.redhat.com/cgi-bin/hg-virt.cgi/applications/virtinst--devel/file/5d6dc8af58b5/virt-install#l209 - Cole _______________________________________________ et-mgmt-tools mailing list et-mgmt-tools@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/et-mgmt-tools
