On Fri, Mar 23, 2012 at 06:01:35PM +0100, Conrad Wood wrote: > on storage: > dd if=/dev/zero of=volume bs=1M : ~ 1,600MByte/s > cp file1 file2 : ~ 300MByte/s (both files on same volume) > > on server > dd if=/dev/zero of=volume bs=1M : ~ 1,100MByte/s > cp file1 file2 : ~ 30MByte/s (both files on same volume) > > Happy with the dd, but it always drops to a tenth of the performance > when I do it with cp.
cp doesn't use large blocks so you'll always get better performance with dd. Try using dd with bs=4k or 32k and see how it stacks up. The coreutils that RHEL ships is pretty old and still uses 4K I/O. We upgraded to coreutils-8.13 which uses 32K blocks and it helps with performance. _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
