Question: I use dd in its simplest form to clone a hard drive:
dd if=INPUT of=OUTPUT
However, I read in the manpage that dd knows a blocksize parameter. Is there an optimal value for the blocksize parameter that will speed up the cloning procedure?
Answer: 64k seems to be a good pick:
Results: ?no bs= ?78s ?144584+0 records ?bs=512 ?78s ?144584+0 records ?bs=1k ?38s ?72292+0 records ?bs=2k ?38s ?36146+0 records ?bs=4k ?38s ?18073+0 records ?bs=5k ?39s ?14458+1 records ?bs=50k ?38s ?1445+1 records ?bs=500k ?39s ?144+1 records ?bs=512k ?39s ?144+1 records ?bs=1M ?39s ?72+1 records ?bs=5M ?39s ?14+1 records ?bs=10M ?39s ?7+1 records
(taken from here).
this matches with my own findings regarding read/write buffering for speeding up an io-heavy converter-program i was once pimping @work.