It works once I use a single VG. However the performance is exactly the same as the backing hard disk, not the SDD. It seems I'm getting no benefit ... # lvs [...] testoriginlv vg_guests Cwi-a-C--- 100.00g lv_cache [testoriginlv_corig] # mount /dev/vg_guests/testoriginlv /tmp/mnt # cd /tmp/mnt # dd if=/dev/zero of=test.file bs=64K count=100000 oflag=direct 100000+0 records in 100000+0 records out 6553600000 bytes (6.6 GB) copied, 57.6301 s, 114 MB/s # dd if=test.file of=/dev/zero bs=64K iflag=direct 100000+0 records in 100000+0 records out 6553600000 bytes (6.6 GB) copied, 47.6587 s, 138 MB/s (Exactly the same numbers as when I tested the underlying HDD, and about half the performance of the SDD.) Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html _______________________________________________ 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/
