Re: [CentOS] Solved Re: imaging a drive with dd

On Mar 3, 2017, at 10:49 AM, Lamar Owen lowen@pari.edu wrote:

On 03/02/2017 11:57 PM, Robert Moskowitz wrote:

...

The following worked:

# dd if=/dev/sdb of=cubietruck.img bs=512 count=6268927

6268927+0 records in 6268927+0 records out 3209690624 bytes (3.2 GB, 3.0 GiB) copied, 114.435 s, 28.0 MB/s

So bs= IS the drive blocksize.

This is the result of trying a number of different values for bs and count.

You can set bs to a multiple of 512 and it will go a lot faster.

Maybe, maybe not. OP said he’s on an embedded system, which often implies low-end eMMC or SD type storage, and 28 MB/sec is typical for such things.

When mirroring HDDs and proper SSDs, yes, you want to use large block sizes.