Heckroth Industries

Always remember the block size option on dd

I am currently having to copy one 50GB partition over another 50GB partition. dd is great for this but the first time I did this I forgot to set the block size so dd defaulted to 512 bytes. An hour and 10 minutes later dd finished. The second time I remembered to set it to 20MB (just add bs=20M as one of the parameters for dd) and it took just under 9 minutes. Just to see what difference it makes I ran it a third time with a block size of 40MB and it took just over 7 minutes.

In the future I really should try harder to remember to set the block size when using dd.

Linux dd
Jason — 2010-07-27