On Thu, May 29, 2014 at 05:06:48PM -0400, Mike Snitzer wrote: > On Thu, May 29 2014 at 4:47pm -0400, > Richard W.M. Jones <rjones@redhat.com> wrote: > > To be clear, that means I should do: > > > > lvcreate -L 1G -n lv_cache_meta vg_guests /dev/fast > > lvcreate -L 229G -n lv_cache vg_guests /dev/fast > > lvconvert --type cache-pool --poolmetadata vg_guests/lv_cache_meta vg_guests/lv_cache > > blkdiscard /dev/vg_guests/lv_cache > > lvconvert --type cache --cachepool vg_guests/lv_cache vg_guests/testoriginlv > > > > Or should I do the blkdiscard earlier? > > You want to discard the cached device before you run fio against it. > I'm not completely sure what cache-pool vs cache is. But it looks like > you'd want to run the discard against the /dev/vg_guests/testoriginlv > (assuming it was converted to use the 'cache' DM target, 'dmsetup table > vg_guests-testoriginlv' should confirm as much). I'm concerned that would delete all the data on the origin LV ... My origin LV now has a slightly different name. Here are the device-mapper tables: $ sudo dmsetup table vg_guests-lv_cache_cdata: 0 419430400 linear 8:33 2099200 vg_guests-lv_cache_cmeta: 0 2097152 linear 8:33 2048 vg_guests-home: 0 209715200 linear 9:127 2048 vg_guests-libvirt--images: 0 1677721600 cache 253:1 253:0 253:2 128 0 default 0 vg_guests-libvirt--images_corig: 0 1677721600 linear 9:127 2055211008 So it does look as if my origin LV (vg_guests/libvirt-images) does use the 'cache' target. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/ _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
