If you want to restore the drive in the future you would use this: # dd if=/dev/sda ibs=4096 | gzip > conv=noerror This will copy the entire drive to a compressed image file. The Noerror flag means to keep going if there is an error. The Notrunc flag means ‘do not truncate the output file’. If it is a larger drive the copy will now be formatted the same as the original, and there won’t be any space left on the drive. Ideally the second hard drive should be the exact same size. Now for examplesĬloneing one hard drive directly to another hard drive:ĭd if=/dev/sda of=/dev/sdb bs=4096 conv=notrunc,noerror This can be done by booting into a live linux CD like knoppix. It is a good idea for the drive that is to be copied to be in read only mode. Most of these catosrophic data destroying events are caused by reversing the input with the output. ![]() Dd is so notorious for destroying data due to mis-typed commands that many people call it data destroy or disk destroy instead of its true name, data definition. It is absolutely imperative that you understand the basic structure of the command. Now that you are aware that dd is not typically used for regular imaging I will describe how you can use it for creating an exact duplicate of your hard drive. But it doesn’t support restoring entire drives. If you are prefer to use free open source solutions, partimage would be a good alternative. Instead you should consider using Norton Ghost or Acronis True Image. This is why DD is not necessarily the best solution for home imaging. “Zeroing out” the unused portion of the drive adds unneeded writing to the drive which could shorten the lifespan of the drive some what. What would normally be a few gigabytes of extra useless space could be reduced to a few kilobytes after you zero it out. This will make compression for that part of the drive incredibily small. Often times people will “zero out” the unused portions of the drive before imaging. The dd image file can be compressed to save space. This is one of the reasons that makes it a good tool for forensics but not so great for home users because that extra data that doesn’t need to be copied adds for a larger image file in the end. So what this means is that dd is making copies of data that remains on the hard drive long after you delete it. The reason for this is because dd literally makes exact copies of the hard drive it self not the actual data. ![]() Can we use dd to create digital copies of our hard drives for backup reasons? Yes we can, and I actually find that it is easier to use than commercially available solutions.ĭd is not always the best solution for regular imaging of hard drives. ![]() For this reason it is often the tool for which all other tools are compared to. Make a Backup Image of your Hard Drive with DD Written by Mark Sanborn: Apr 4, 2008ĭd is a tool that is often used in computer forensics because it is extremly low level and effecient at creating exact duplicates of hard drives.
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