Re: Some help with dd backing up into an iso
- Date: Tue, 7 Mar 2017 10:04:25 +0000
- From: Jonathan Dowland <jmtd@xxxxxxxxxx>
- Subject: Re: Some help with dd backing up into an iso
On Tue, Mar 07, 2017 at 10:26:25AM +0200, Teemu Likonen wrote: > What's the point of using dd? > > gzip </dev/sda >myimage.img > > I don't know about you but many people seem to think that dd is some > kind of special tool for reading and writing block device files. But > after all the devices are just files that can be read with normal > commands like cat or cp. These are even faster normally because they use > larger buffers. Write operations on device files should be finished with > sync command to flush the buffers. You're right, but I would advocate people use gddrescue instead, rather than cp etc., since (unlike cp, cat, dd, etc.) gddrescue is very careful about which blocks it has read, can do retries, keeps a log file, can be interrupted and resumed safely, and can recover data from failing devices. -- Jonathan Dowland Please do not CC me, I am subscribed to the list.
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