On Fri, May 13, 2011 at 9:47 PM, Andrey Moshbear <andrey....@gmail.com> wrote: > On Fri, May 13, 2011 at 18:35, Mick <michaelkintz...@gmail.com> wrote: >> On Friday 13 May 2011 20:11:01 James Wall wrote: >>> >>> Another tool which will work well is dd. >>> as an example to back up my laptop before experimenting with new >>> distros, I do dd if=/dev/sda of=/mnt/backup/jalopy.img bs=2M to back >>> up the drive for a bare metal restore of the 40 GB hard drive. >>> >> >> Is the bs=2M important? Should one use the block size of the drive? > Speed improvement. > If you're doing a backup of a rather large disk, I duggest piping to > bzip2 or gzip. Unless the free space is random padding, even the > slightest > compression will be more efficient, space-wise, than the raw file. The > big problem is bzip2 -9, because you only get ~2.5 MB/s compression > speed. > >
I set the bs=2M to the size of the hdd cache to push it to the limit of speed. YMMV, the best thing to do is experiment. You may find a different number works better. James Wall
