What does DD bs do and whats the maximum i should set it as?

[TheYikes2]

hello again! I'm looking at the dd command on kubuntu, I know it's a dangerous tool in the wrong hands but I think I have a fair idea of what I'm doing. I know from the man page that bs is bs=BYTES read and write up to BYTES bytes at a time (default: 512);
is there a maximum setting for this and if so how can i tell?

[jlittle]

The block size just says how much data dd reads or writes at a time. It can go a lot faster with, say, bs=1M. I suspect the maximum would be limited by how much free RAM is available.

dd is an ancient command. Originally, the block size was primarily the block size on magnetic tape, or the like.

[Snowhog]

dd is an ancient command.

Yup. 50 years old (so far). https://en.wikipedia.org/wiki/Dd_(Unix)

[TheYikes2]

Good lord that response was quick!! Ok so i guess dd is deprecated, any clue as to whjat i should be using instead? oh and thanks by the way for the hasty response!

[Qqmike]

Nothing wrong with dd at all. It does what you tell it to do.

My how-to/experiments with it:

The dd Command
https://www.kubuntuforums.net/forum/...the-dd-command

[Snowhog]

dd is deprecated

What makes you think that? Old/ancient doesn't imply deprecated. dd is as relevant today, as it was then.

[TheYikes2]

Hey Again Snowhog. I was just basing it on what I read. I honestly don't know why but I'm actually addicted to linux. Is there anything other than dd? I'm only asking because i have to update my ssd to a nvme drive.

[oshunluvr]

Is there anything other than dd? I'm only asking because i have to update my ssd to a nvme drive.

Yes, there are tools like Clonezilla and Gparted which can do that. Depending on the file system and what you're actually moving, rsync may be an option also.

Frankly, they're all safer options than dd. The nickname for dd is "data destroyer" because there's no safety checks - a wrong character or 2 and you've wiped your drive.

[GreyGeek]

IF you have to ask what dd is, or how to use it, I suggest you not use it until you learn how. Do that on another installation, or in a VM, until you have mastered it.

[Qqmike]

I agree with GreyGeek.
I took a special interest in dd, thus my extensive how-to list of examples.
BUT ... anyone doing this should/must start out with harmless "toy examples" that you have total control over.
(I have made serious mistakes by working too fast and hitting the GO button without looking.)