On 4/21/2010 10:18 AM, Ray Morris wrote: > pvmove is good for when you have to keep the machine > live during the copy. dd is about 10 times as fast if you > can be down during the copy. This specific dd invocation > is the fastest I've found for the purpose, running 2-3 times > faster than a simple dd without arguments: > > dd if=/dev/old_vg/$1 bs=64M iflag=direct | dd of=/dev/new_vg/$1 bs=64M > oflag=direct What arguments are best depend on many factors. These particular ones should be rather good if the src and and dest volumes are on the same physical disk. It would not be very good if they are on different disks, since while dd is reading from the source, the output disk is idle, and vice versa. If src and dest are different disks, then you want to not use direct, and stick with a more reasonable block size, say 64k. Also if the fs has much free space in it then dd will waste a lot of time on that. You probably would save a lot of time doing something like dump | restore. This also does not require that the source and destination be the same size. _______________________________________________ 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/
