Wednesday, November 13, 2013

Disk data backup using dd

Yesterday I saw the message pop-up "Hard driver failure blah blah ~". "Smart Data" utility said that replace my hard drive immediately.

Main reason is "reallocated sector count warning". increasing Bad sector.

There are so many posting about this issue

Most of posting recommend that I should replace my hard disk immediately. Only few postings say the warning can be handled by recent system, so I can use my disk longer before more crucial waning occurs. But they also recommend data backup.

So I decided to replace my HDD. Because I'm not busy, I thought that I did it relaxedly.

My colleague recommended to use "dd"(disk dump") This tool clones a HDD as a block device, so I don't need to re-install OS.

I accepted his advice. I insert a new HDD and old one with same bland & same size but different versions.  And I type the following command

dd if=/dev/sdb of=/dev/sda

I regretted my decision. Because dd is not gui tool, there is no fancy display, so I could not check current status.

I asked the colleague How long it will take. He don't know it!!! He just knew about that, did not have used it.
I'm upset. What I could do was just watching "dd"'s CPU occupation info using "top". It was steadily 30%. I tried to search for information of the performance of "dd" command on the webs. but I found nothing.

It took 28800 seconds, almost 8 hours for cloning 1 TB !!!!!

I didn't do any thing yesterday!!!

One of my friend recommends to use "bs=1m" option for "dd". And another colleague recommends a specialized hardware cloning HDD called "clone1". It's chip and fast and can be used as a external HDD adapter.

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