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 _______________________________________________ et-mgmt-tools mailing list et-mgmt-tools@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/et-mgmt-tools
